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Allow Coroutine_Run to return a failure
jonroach 15 Dec 2025 12:31
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9 months ago
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 Stackful coroutines in C.
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 * `Task` & `Future` coroutines which can pause, waiting for a future.
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 * `ASleep` an example of pausing `Task`s using `Future`s.
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 * `Generator` coroutines used as generators for loops.
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 * `Coroutine` the base coroutine engine.
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 Your code doesn't need to do anything special to be a coroutine. Only standard, or commonly available libraries are needed.
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 ## Prerequisites
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 These libraries rely on as much as possible on C's cross-platform comfort zone. C's standard libraries are used as far as possible, but, as `threads.h` is not usually supported, `pthread.h` has been used instead.
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 You will need to build & link the code, `coroutine/*.c`, as part of your system, and ensure the headers, `include/*`, are available on your include path.
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 If your system doesn't have pthread, all the system-specific bits have been collected into cor_platform.c & .h. Replace these with versions which work with your platform.
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 ## Quick Start
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 ### Tasks
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 To run `Task`s:
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 #!C
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 #include "coroutine.h"
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 #include "task.h"
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 main(){
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 Coroutine_StartSystem();
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 void *res = NULL;
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 bool canceled = Task_Run(maintask, &param, &res);
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 Coroutine_StopSystem();
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 }
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 `Task_Run` runs tasks, switching between them when the current task waits on an `Future`. `maintask()` is run as a task. The start function for any task looks like this:
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 #!C
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 bool mytask(void *param, void **res){
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 // do your thing here
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 return canceled;
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 }
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 When `Task` returns from its start function, it returns whether it was canceled. Canceled `Task`s are assumed to have not finished what they were doing.
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 Within your main task, create `Task`s and `Task_Await()` them when you want to wait for their result:
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 #!C
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 Task task1;
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 Task_ctor(&task1, adifferenttask, &task1param);
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 void *result;
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 bool canceled = Task_Await(&task1, &result);
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 Task_dtor(&task1);
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 // use the result
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 When a task needs to wait for something, and wants to allow other tasks to run, it should use a `Future`:
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 #!C
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 Future future;
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 Future_ctor(&future);
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 // pass the future to the background-thing-which-might-take-a-while
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 void *res;
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 bool canceled = Future_Await(&future, &res);
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 Future_dtor(&future);
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 When the background-thing-which-might-take-a-while has a result:
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 #!C
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 Future_SetResult(future, false, result);
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 ### ASleep
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 `ASleep()` needs its own system to be started to work:
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 #!C
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 ASleep_StartSystem()
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 Coroutine_StartSystem();
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 // Run tasks here which may now use ASLeep()
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 Coroutine_StopSystem();
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 ASleep_StopSystem();
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 Note that `ASleep_StartSystem()` / `ASleep_StopSystem()` is only needed once per process, whereas `Coroutine_StartSystem()` / `Coroutine_StopSystem()` is needed on each thread where coroutines are used.
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 Sleeping in a task:
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 #!C
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 bool mytask(void *param, void **result){
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 ..
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 ASleep(time_to_sleep);
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 ..
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 }
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 ### Generators
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 The coroutine system needs to be started:
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 #!C
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 Coroutine_StartSystem();
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 // you can use generators now
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 Coroutine_StopSystem();
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 or
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 #!C
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 void *mygenuser(void *){
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 // use generators here
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 }
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 if (Coroutine_Run(mygenuser, NULL, NULL)){
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 // handle the failure
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 }
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 Note that you need to start the coroutine system on each thread you want to use them.
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 You will need a generator function:
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 #!C
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 void *yield_my_things(void *param){
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 bool domore = true;
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 // loop/call functions to find more values to yield, and when you have one:
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 domore = Generator_Yield(thing);
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 // .. if domore is false, exit your generator - it is being destructed
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 // not actually used by generators, but this is a useful convention for bubbling
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 // the flag out to calling functions.
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 return (void *)domore;
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 }
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 And to use it:
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 #!C
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 Generator gen;
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 Generator_ctor(&gen, yield_my_things, "..");
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 void *thing;
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 while(Generator_Next(&gen, &thing)){
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 // use thing - a value yielded by your generator
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 }
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 Generator_dtor(&gen);
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 ### Coroutines
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 While you can use coroutines directly, it's designed as a system to support more useful patterns, like `Async` and `Generators`.
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 The Coroutines system must be started:
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 #!C
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 Coroutine_StartSystem();
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 // use coroutines here
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 Coroutine_StopSystem();
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 Your coroutine will need to have a start function:
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 #!C
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 void *start(void *param){
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 ...
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 }
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 When there is no coroutine running, start your 'main' coroutine:
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 #!C
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 // Coroutine_StartSystem() is optional.
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 // Wrap with Coroutine_StartSystem() & Coroutine_StopSystem() to get the report
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 void *result;
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 if (Coroutine_Run(comain, param, &result)){
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 // handle the failure
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 }
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 Create other coroutines like this:
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 #!C
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 Coroutine *cor = Coroutine_New(start);
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 When you want a Coroutine to run, or to return from a yield:
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 #!C
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 Coroutine_Continue(cor, value, run_early);
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 `value` will be start function's parameter, or the value returned from the yield.
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 Within the Coroutine, to yield a value:
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 #!C
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 void *Coroutine_Yield(value, on_yield, void *me);
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 The on_yield function is called after the coroutine has been 'wait'ed, but before the next coroutine is resumed.
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 ## How it Works
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 The coroutine system uses the stack divided into smaller stacks for the coroutines. This means you may need to consider whether the coroutine stack size, set by `COROUTINE_STARTUP_STACK_SIZE`, is right for your application, and whether your stack size is enough for the number of coroutines you might run.
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 Each of your threads has its own stack - the coroutine system can be run (or not) independantly on each thread. For some special cases, you may want to adjust each of your thread's stack sizes depending on how it is used.
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 ## Style
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 The style is influenced by C++. For example, where possible, a `Something *Something_New(a, b, c)` and `Something_Delete(Something *)` will have corresponding `Somthing_ctor(Somthing *, a, b, c)` and `Something_dtor(Something *)` to initialise and finalise a `Something` on the stack, or within another object. Using `.._ctor()` and `.._dtor()` will be faster as they avoid the `malloc()` and `free()`.
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 #!C
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 Something *oneofthem = Something_New();
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 // use oneofthem
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 Something_Delete(oneofthem);
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 Can be also be done like this, and this will run faster:
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 #!C
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 Something oneofthem;
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 Something_ctor(&oneofthem);
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 // use oneofthem
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 Something_dtor(&oneofthem);
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 The exception is `Coroutine_New()` and `Coroutine_Delete()`. The returned `Coroutine` is somewhere on your thread's stack - its memory is managed by the coroutine system, and is allocated and freed quickly.
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 ## Usage
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 When you are using coroutines or generators:
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 #!C
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 void *myfunc(void *){
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 // your function here
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 }
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 Coroutine_StartSystem();
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 if (Coroutine_Run(myfunc, (void *)myparam, NULL)){
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 // handle the failure
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 }
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 Coroutine_StopSystem();
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 While the system is started, you can make many calls to `Coroutine_Run()` or `Task_Run()`, but only one of them can be running at once. A running system is thread local - each thread you want to use coroutines on will need to be `Coroutine_StartSystem()`ed.
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 ## Stack Overruns
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 The C stack is divided down into smaller stacks. There's one to give some work room between `..StartSystem()` and `..Run()`, and one for each coroutine. These have guard markers which are checked to see if the stack has overrun. If there is a stack overrun, the system cannot continue - a message is output and the programe exited. There's a number of ways to avoid this issue:
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 * Use less stack. This is, sometimes, the right advice, especially if the startup stack overrins. The expectation is that very little is done between `.._StartSystem()` and `..Run()`. If your situation needs more doing, you can...
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 * increase the stack size. Adjust `COROUTINE_STACK_SIZE` (for startup) or `COROUTINE_STARTUP_STACK_SIZE` (for coroutines) as appropriate. If your use case is even more demanding, such as if you want 1000s of coroutines (so you need small stack chunks), /and/ some of them can recurse an unknown amount (so you need a deep stack for that coroutine), then you can...
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 * monitor stack headroom, and add another stack chunk if you need to:
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 In this last case you'll need to add some code at key points:
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 #!C
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 void *myfunction(void *param){
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 if (Coroutine_GetStackHeadroom() < MIN_ALLOWED_STACK){
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 return Coroutine_Chain(myfunction, param);
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 }
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 // do everything normally
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 }
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 More realistically:
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 #!C
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 struct myfunctionparams {
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 int a;
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 char *b;
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 struct dog *d;
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 }
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 void *mychain(void *param){
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 struct myfunctionparams *myparams = (struct myfunctionparams *)params;
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 return (void *)myfunction(myparams->a, myparams->b, *myparams->d);
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 }
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 int myfunction(int a, char *b, struct dog d){
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 if (Coroutine_GetStackHeadroom() < MIN_ALLOWED_STACK){
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 struct myfunctionparams params = {
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 a,
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 b,
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 &d
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 };
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 return (int)Coroutine_Chain(mychain, &params);
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 }
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 }
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 And if you want to panic if the C stack overruns:
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 #!C
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 if (Coroutine_GetStackHeadroom() < MIN_ALLOWED_COROUTINE_STACK){
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 if (Coroutine_HasCoroutinesInFreePool() ||
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 (char *)Coroutine_GetCStackTop() - c_stack_end >= MIN_ALLOWED_C_STACK) {
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 struct myfunctionparams params = {
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 a,
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 b,
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 &d
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 };
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 return (int)Coroutine_Chain(mychain, &params);
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 }
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 // panic now
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 }
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 # API
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 ## Task & Future
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 The pattern for using async is:
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 #!C
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 bool mymaintask(void *param, void **result){
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 // do your main task things here, like starting more tasks
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 }
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 Coroutine_StartSystem();
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 void *res = NULL;
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 bool canceled = Task_Run(mymaintask, NULL, &res);
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 Coroutine_StopSystem();
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 To create and wait for a task:
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 #!C
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 Task task1;
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 Task_ctor(&task1, asynctask1, &task1param);
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 void *res = NULL;
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 bool canceled = Task_Await(&task1, void **res)
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 Task_dtor(&task1);
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 or, if you prefer new & delete:
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 #!C
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 Task *task1 = Task_New(asynctask1, &task1param);
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 void *res = NULL;
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 bool canceled = Task_Await(task1, void **res)
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 Task_Delete(task1);
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 Inside your task, when there is something to wait for and you want other tasks to run while your task is waiting, you will need a future:
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 #!C
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 Future future;
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 Future_ctor(&future);
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 // keep &future to hand for when the background thing completes
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 bool canceled = Future_Await(&future, NULL);
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 Future_dtor(&future);
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 `Future_New()` and `Future_Delete()` are also available if you prefer that style.
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 Inside the callback when the background thing is complete:
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 #!C
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 // result is a void *
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 Future_SetResult(future, result, false);
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 or, if something went wrong:
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 #!C
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 // exception is a void *
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 Future_SetResult(future, exception, true);
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 Back in the task, you can respond to the future:
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 #!C
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 ... Future_Await has returned
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 if (canceled){
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 // exit quickly - you've been canceled
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 // you could, for example, use the future's result as an exception, or error code here
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 }
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 // carry on - the future's result may be an actual result, that's up to you
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 ##### void Future_ctor(Future *fut)
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 fut
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 : The `Future` being constructed
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 Initialise a future. When you no longer need it, use `Future_dtor()`.
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 ##### Future *Future_New()
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 (returns)
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 : The new future
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 Allocates and initialises a future, When you no longer need it, use `Future_Delete()`.
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 ##### void Future_dtor(Future *fut)
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 fut
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 : The `Future` being destructed
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 Destruct a future previously constructed with `Future_ctor()`.
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 ##### void Future_Delete(Future *fut)
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 fut
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 : The `Future` to be destructed and freed
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 Delete (finalise and free) a future previously new'ed with `Future_New()`
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 ##### void Future_SetResult(Future *fut, bool canceled, void *value)
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 fut
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 : The `Future` whose result is being set
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 canceled
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 : The future's `canceled` setting
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 value
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 : The future's result `value`
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 Set the result of a future. This has an effect only the first time its done, ie a completed future can't be canceled and a canceled future can't be completed. When an `Future` has a result, its watchers are called back.
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 The `value` of a future might be a result if the future completes (when `canceled == false`), or could be some sort of exception value if `canceled == true`. The interpretation of a future's `value` is up to the user - as far as the async system is concerned, it's only a `void *`.
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 ##### bool Future_GetResult(Future *fut, void **res)
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 (returns)
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 : The `canceled` value of the `Future`.
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 res
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 : Where to store the value of the `Future`. This may be `NULL`.
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 Get the result of a future.
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 ##### typedef void (*Future_Watcher)(void *me, Future *fut)
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 A `Future_Watcher` is a callback called when a future has a result. The `me` parameter is the one passed to `Future_AddWatcher()`. `fut` is the future which has just got its result.
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 ##### void Future_AddWatcher(Future *fut, Future_Watcher watcher, void *me)
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 fut
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 : the `Future` to add a watcher to
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 watcher
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 : the callback to call when the `Future` has a result.
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 me
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 : the `me` value to pass to `watcher` when it is called back.
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 Add a watcher (callback) to be called when the future has a result. If the future is already complete, `watcher` is immediately called. The `me` value is passed to the watcher as its `me` parameter. It is assumed that a watcher, identified by the `(watcher, me)` pair, will only be added once.
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 ##### void Future_RemoveWatcher(Future *fut, Future_Watcher watcher, void *me)
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 fut
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 : the `Future` to remove a watcher from
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 watcher
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 : the callback of the watcher to remove.
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 me
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 : the `me` value of the watcher to remove.
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 Remove a watcher from a future. It is not an error if no watcher matching `(watcher, me)` is found - it has probably already been called back.
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 ##### bool Future_Await(Future *fut, void **res)
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 (returns)
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 : whether the `Future` was canceled.
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 fut
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 : The `Future` to wait for.
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 res
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 : Where to store the `value` of the future when it is has a result. May be `NULL`.
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 The current `Task` is paused until the `Future` has a result. Other `Task`s are run while this one is waiting.
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 ##### typedef bool (*Task_Entry)(void *param, void **res)
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 The entry function to an `Task`.
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 ##### void Task_ctor(Task *tsk, Task_Entry entry, void *param)
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 tsk
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 : The task to construct.
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 entry
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 : The entry function for the task.
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 param
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 : The value for `param` to pass to `entry`.
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 Initialises an `Task`. When you have finished with an `Task` you must finalise it using `Task_dtor()`
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 #!C
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 Task tsk;
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 Task_ctor(&tsk, mytask, myparam);
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 // tsk will run if you wait for a task or future
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 Task_Await(&tsk, NULL);
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 Task_dtor(&tsk);
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 ##### Task *Task_New(Task_Entry entry, void *param)
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 (returns)
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 : The new `Task`.
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 entry
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 : The entry function for the task.
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 param
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 : The value for `param` to pass to `entry`.
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 This allocates and initialises a new `Task`. When you have finished with your task, you must `Task_Delete()` it.
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 #!C
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 Task *tsk = Task_New(mytask, myparam);
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 // tsk will run if you wait for a task or future
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 Task_Await(tsk, NULL);
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 Task_Delete(tsk);
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 ##### void Task_dtor(Task *tsk)
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 tsk
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 : The `Task` to destruct.
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 This finalises an `Task` you ealier initalised with `Task_ctor()`. It is an error to attempt to destruct a task which is running.
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 #!C
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 Task tsk;
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 Task_ctor(&tsk, mytask, myparam);
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 // use tsk
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 Task_dtor(&tsk);
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 ##### void Task_Delete(Task *tsk)
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 tsk
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 : The `Task` to delete.
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 This finalises and frees an `Task` you ealier new'ed with `Task_New()`. It is an error to attempt to delete a task which is running.
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 #!C
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 Task *tsk = Task_New(mytask, myparam);
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 // use tsk
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 Task_Delete(tsk);
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 ##### static inline bool Task_Await(Task *tsk, void **res)
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 (returns)
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 : Whether the task was canceled.
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 tsk
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 : The `Task` to wait for.
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 res
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 : Where to store the `Task`'s value when it finishes. This may be NULL.
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 The current `Task` waits for `tsk` to finish, and returns the result.
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 ##### void Task_Cancel(Task *tsk, void *cancel_value)
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 tsk
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 : The task to cancel.
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 cancel_value
549
 : The value to set on any future this task waits on.
550
551
 This marks a task as canceled. When that task waits on a future that future will be canceled too, using `cancel_value`.
552
9 months ago
553
 ##### static inline bool Task_IsCanceled(Task *tsk)
9 months ago
554
555
 (returns)
556
 : Whether the task is canceled.
557
558
 tsk
559
 : The task to get its canceled setting from.
560
9 months ago
561
 ##### static inline Future *Task_GetAwaitedFuture(Task *tsk)
9 months ago
562
9 months ago
563
 (returns)
564
 : The future the task is waiting on. May be NULL.
565
566
 tsk
567
 : Teh task to read the future it is waiting on.
568
569
 Return the future a task is waiting on.
570
9 months ago
571
 ##### bool Task_Run(Task_Entry start, void *value, void **res)
9 months ago
572
573
 (returns)
9 months ago
574
 : Whether `start` was canceled.
9 months ago
575
9 months ago
576
 start
577
 : The function to use as the main task.
9 months ago
578
579
 value
9 months ago
580
 : The value to pass to `start`.
9 months ago
581
9 months ago
582
 res
583
 : Where to store the result of `start`.
9 months ago
584
9 months ago
585
 Runs `start` as an `Task`. When `start` returns all other tasks must have been destructed, using `Task_dtor()` or `Task_Delete()`.
9 months ago
586
9 months ago
587
 ## ASleep
9 months ago
588
9 months ago
589
 ##### void ASleep_StartSystem()
9 months ago
590
9 months ago
591
 You must start the `ASleep` system to use it. This needs to happen per process (whereas `Coroutine_StartSystem()` needs to happen per-thread). Once you've finished with `ASleep` you must `ASleep_StopSystem()`.
9 months ago
592
9 months ago
593
 #!C
9 months ago
594
 ASleep_StartSystem();
595
 // Now you can use ASleep() on any thread
596
 ASleep_StopSystem();
9 months ago
597
9 months ago
598
 ##### void ASleep_StopSystem()
9 months ago
599
9 months ago
600
 Call this to stop the `ASleep` system.
9 months ago
601
9 months ago
602
 ##### bool ASleep(float delay, void **value)
9 months ago
603
9 months ago
604
 (returns)
605
 : Whether the task was canceled.
9 months ago
606
9 months ago
607
 delay
608
 : How many seconds to delay for.
9 months ago
609
9 months ago
610
 value
611
 : Where to store the cancellation value. This may be NULL.
9 months ago
612
9 months ago
613
 Sleep for `delay` seconds. `*value` will be set to `NULL` if the sleep is successful, and the `cancel_value` if the task is canceled.
9 months ago
614
9 months ago
615
 ## Generator
9 months ago
17
616
9 months ago
617
 The pattern for a `Generator` is:
618
9 months ago
619
 #### A loop which uses the `Generator
9 months ago
620
9 months ago
621
 #!C
9 months ago
17
622
 Generator gen;
9 months ago
623
 Generator_ctor(&gen, mygen, &param);
9 months ago
17
624
9 months ago
625
 void *value;
626
 while(Generator_Next(&gen, &value)){
627
 // use value here
9 months ago
17
628
 }
9 months ago
629
 // value is now the return value from the Generator
630
9 months ago
17
631
 Generator_dtor(&gen);
632
9 months ago
633
 Or:
9 months ago
17
634
9 months ago
635
 #!C
9 months ago
636
 Generator *gen = Generator_New(mygen, &param);
9 months ago
17
637
9 months ago
638
 void *value;
639
 while(Generator_Next(gen, &value)){
640
 // use value here
641
 }
9 months ago
17
642
9 months ago
643
 Generator_Delete(gen);
9 months ago
17
644
9 months ago
645
 `Generator`s yield a series of `void *`s - what the `void *`s mean is up to you. `Generator_Next()` returns a `bool` to indicate whether the `Generator` has finished.
9 months ago
17
646
9 months ago
647
 #### A generator function
9 months ago
17
648
9 months ago
649
 #!C
9 months ago
650
 void *mygen(void *param){
651
 bool domore = true;
652
 // The parameter is a pointer to a string of chars
653
 for (char *str = param; *str; ++str) {
654
 // The value yielded is a pointer to a character in the string
655
 domore = Generator_Yield(str);
656
 if (!domore){
657
 break;
658
 }
659
 }
660
661
 return (void *)domore;
9 months ago
17
662
 }
663
9 months ago
664
 The `bool` returned from `Generator_Yield()` indicates whether the generator function should yield more values. When it is `false` the `Generator` is being finalised - your generator function should close files, and release any other resources it has claimed, before exiting.
9 months ago
17
665
9 months ago
666
 ##### void Generator_ctor(Generator *gen, void *(*start)(void *), void *param)
9 months ago
17
667
9 months ago
668
 gen
669
 : The `Generator` to construct.
9 months ago
17
670
9 months ago
671
 start
672
 : The function which is the start/entry-point of the `Generator`.
673
674
 param
675
 : The value to pass to `start`.
676
677
 Initialise a `Generator`. When you no longer need the `Generator`, use `Generator_dtor()` to destruct it.
678
9 months ago
679
 #!C
9 months ago
680
 Generator gen;
681
 Generator_ctor(&gen, mystart, &params);
9 months ago
17
682
9 months ago
683
 // Generator is used
9 months ago
17
684
9 months ago
685
 // ... later:
686
 Generator_dtor(&gen);
687
9 months ago
688
 ##### Generator *Generator_New(void *(*start)(void *), void *param)
9 months ago
689
9 months ago
690
 start
691
 : The function which is the start/entry-point of the `Generator`.
9 months ago
692
9 months ago
693
 param
694
 : The value to pass to `start`.
695
696
 `new` a `Generator` - malloc, and initialise it. When you no longer need the `Generator` use `Generator_dtor` to finalise it.
697
9 months ago
698
 #!C
9 months ago
699
 Generator *gen = Generator_New(mystart, &params);
700
701
 // Generator is used
702
703
 // ... later:
704
 Generator_Delete(gen);
705
9 months ago
706
 ##### void Generator_dtor(Generator *gen)
9 months ago
707
9 months ago
708
 gen
709
 : The `Generator` to destruct.
710
9 months ago
711
 Finalise a `Generator`. Once a `Generator` is no longer needed, it must be finalised:
712
9 months ago
713
 #!C
9 months ago
714
 // earlier...
715
 Generator gen;
716
 Generator_ctor(&gen, mystart, &params);
717
718
 // Generator is used
719
720
 // the Generator is no longer needed
721
 Generator_dtor(&gen);
722
723
9 months ago
724
 ##### void Generator_Delete(Generator *gen)
9 months ago
725
9 months ago
726
 gen
727
 : The `Generator` to delete.
728
9 months ago
729
 Finalise then `free()` a `Generator`. Once a `new`ed `Generator` is no longer needed, it must be deleted:
730
9 months ago
731
 #!C
9 months ago
732
 // earlier...
733
 Generator *gen = Generator_New(mystart, &params);
734
735
 // Generator is used
736
737
 // the Generator is no longer needed
738
 Generator_Delete(gen);
739
740
9 months ago
741
 ##### bool Generator_Next(Generator *gen, void **value)
9 months ago
742
9 months ago
743
 (returns)
744
 : Whether there is a next value. `true` - there is a next value; `false` - the `Generator` has finished
745
746
 gen
747
 : The `Generator` to get the next value from.
748
749
 value
750
 : Where to store the next value.
751
9 months ago
752
 Get the next value yielded by the `Generator`.
753
9 months ago
754
 #!C
9 months ago
755
 void *value;
756
 while(Generator_Next(gen, &value)){
757
 // use value here
9 months ago
17
758
 }
9 months ago
759
9 months ago
760
 The `Generator` feeds values to its client using `Generator_Yield()` - it is these values which `Generator_Next()` sets, in the example, `value` to.
9 months ago
761
9 months ago
762
 When a `Generator` is finished it returns from `start`. When you call `Generator_Yield()` on a finished `Generator` it returns `false` and `value` will be the return value from `start`.
763
9 months ago
764
 ##### bool Generator_Yield(void *value)
9 months ago
765
9 months ago
766
 (returns)
767
 : Whether the `Generator` should do more.
9 months ago
768
9 months ago
769
 value
770
 : The `Generator`'s next value.
771
772
 Yield a value from a `Generator`.
773
9 months ago
774
 #!C
9 months ago
775
 bool domore = Generator_Yield(value);
776
9 months ago
777
 `value` is then provided by `Generator_Next()` as the next value from the generator.
9 months ago
778
9 months ago
779
 The `bool` returned by `Generator_Yield()` says whether more values should be provided by your generator function. `true` - provide more values if there are any. `false` - close files, free memory, free up any other resources and `return`. `false` is returned when the `Generator` is being finalised before it has finished, ie the client has exited its `for`-loop early.
780
9 months ago
781
 ## Coroutine
782
9 months ago
783
 ##### void Coroutine_StartSystem()
9 months ago
784
7 months ago
785
 Start the coroutine system on this thread. When you've finished with `Coroutine` must call `Coroutine_StopSystem()`.
9 months ago
786
9 months ago
787
 #!C
7 months ago
788
 Coroutine_StartSystem();
9 months ago
789
 // prepare
6 months ago
790
 void *result;
791
 if (Coroutine_Run(..., &result)){
792
 // handle the failure
793
 }
9 months ago
794
 // use result
7 months ago
795
 Coroutine_StopSystem();
9 months ago
796
7 months ago
797
 `Coroutine` can be started & stopped many times. While `Coroutine` is started, `Coroutine_Run()` or `Coroutine_RunCoroutine()` can be called any number of times.
9 months ago
798
799
 The total stack allowed for all coroutines running on any thread is the size of the call stack on that thread.
800
7 months ago
801
 ##### Coroutine_SetStackLimit(void *limit)
802
803
 Set the limit of the stack. This is used to determine more accurately whether `Coroutine_CanStartCoroutine()`
804
9 months ago
805
 ##### Coroutine_Report Coroutine_StopSystem()
9 months ago
806
9 months ago
807
 Stop the coroutine system on this thread. A `Coroutine_Report` is returned, which summarises the coroutine activity on this thread:
9 months ago
808
9 months ago
809
 #!C
9 months ago
810
 typedef struct Coroutine_Report {
811
 unsigned coroutines_created;
812
 unsigned coroutines_pool_size;
813
 unsigned lowest_headroom;
814
 } Coroutine_Report;
815
816
 coroutines_created
817
 : How many coroutines were created
818
819
 coroutines_pool_size
820
 : The size of the coroutine pool (count of available, free `Coroutine` objects) when the system stopped. This is also the peak number of active coroutines. This will give you an idea of how much stack was needed for your coroutines.
821
822
 lowest_headroom
823
 : The lowest headroom (unused bytes before the guard word) any of the coroutine had.
824
9 months ago
825
 ##### Coroutine_Start
9 months ago
826
9 months ago
827
 #!C
9 months ago
828
 void *(*)(void *param)
829
9 months ago
830
 The entry function for a coroutine. The `param` is the value passed to `Coroutine_Continue`, and the `void *` return value can be accessed through the `Coroutine` object using `Coroutine_GetValue()`.
9 months ago
831
9 months ago
832
 ##### Coroutine *Coroutine_New(Coroutine_Start start)
9 months ago
833
6 months ago
834
 Create a new `Coroutine`. The `Coroutine` system must be started to create a `Coroutine`. The stack size available to the coroutine will be `COROUTINE_STACK_SIZE` defined in `coroutine.h`. When you have finished with your `Coroutine`, use `Coroutine_Delete()` to delete it. If there is not enough space for a new `Coroutine` on your stack, `NULL` will be returned.
9 months ago
835
9 months ago
836
 ##### void Coroutine_Run_Coroutine(Coroutine *cor, void *value)
9 months ago
837
7 months ago
838
 Run the `Coroutine` and return when it returns. This is how to start coroutines running in the coroutine system. It is an error for the run coroutine to return before all other coroutines have completed, and the coroutine system must be started to call this.
9 months ago
839
6 months ago
840
 ##### bool Coroutine_Run(Coroutine_Start start, void *value, void **result)
9 months ago
841
6 months ago
842
 `start(value)` is called from within a coroutine and its value returned in `*result`.
843
 If this completes without any failure, `false` is returned, otherwise, typically
844
 because `Coroutine_New()` returned `NULL`, `true` is returned. `result` may be `NULL` if you don't
845
 need the resturn value from `start()`.
846
 When the coroutine system is active - you are already running in a coroutine - `start(value)`
847
 is simply called and its result returned in `*result`. When the Coroutine system is not running,
848
 `Coroutine_Run()` starts it, creates a `Coroutine` and runs that Coroutine to call `start(calue)`
849
 and return value is returned in `*result`, then stops the Coroutine system.
9 months ago
850
9 months ago
851
 ##### void Coroutine_Delete(Coroutine *cor)
9 months ago
852
9 months ago
853
 Use `Coroutine_Delete()` to delete a coroutine when it is no longer needed. It is an error to attempt to delete a coroutine which is running.
9 months ago
854
9 months ago
855
 ##### void Coroutine_Continue(Coroutine *cor, void *value, bool early)
9 months ago
856
857
 Continue the given `Coroutine`. `value` is passed to the coroutine, as `param` to the `start` function, or as the return value from `Coroutine_Yield`. `early` determines whether the continued coroutine is added to the head of tail of the list of runable coroutines.
858
9 months ago
859
 ##### void *Coroutine_Yield(void *value, Coroutine_YieldCallback on_yield, void *this)
9 months ago
860
861
 Yield `value` from the current coroutine; this coroutine is moved to the list of coroutines waiting to be continued. The next runable coroutine is run - either by its start routine being called with `value` as its `param`, or by `value`being returned from its `Coroutine_Yield()`.
862
9 months ago
863
 ##### void *Coroutine_GetValue(Coroutine *cor)
9 months ago
864
865
 Return the `Coroutine`'s value - the value last yielded, or returned by its `start` routine.
866
9 months ago
867
 ##### Coroutine *Coroutine_GetActive()
9 months ago
868
869
 Return whihc coroutine is currently running, ie the caller's `Coroutine`.
870
9 months ago
871
 ##### bool Coroutine_IsRunning(Coroutine *cor)
9 months ago
872
873
 Return whether the given coroutine is still running - it may be running, ready to run, or waiting to be continued, but won't have returned from its `start` function.
9 months ago
874
7 months ago
875
 ##### bool Coroutine_IsComplete(Coroutine *cor)
876
877
 Return whether the given coroutine is complete - is has returned from its `start` function.
878
8 months ago
879
 ##### intptr_t Coroutine_GetStackHeadroom()
9 months ago
880
9 months ago
881
 Return the headroom available in the current coroutine's stack. This can be used to detect when your coroutine is nearing its stack limit, and then use `Coroutine_Chain()` to continue in a new chunk of coroutine stack.
9 months ago
882
7 months ago
883
 ##### bool Coroutine_CanStartCoroutine()
9 months ago
884
7 months ago
885
 Return whether the coroutine system can start a new coroutine. This check can only be done with the coroutine system active (currently running
7 months ago
886
 a coroutine). If there's a free coroutine, or enough space on the stack for a new one, then this will return `true`. To set the limit of the
887
 stack use `Coroutine_SetStackLimit()`
9 months ago
888
7 months ago
889
 ##### void *Coroutine_GetStackHWM(void)
890
891
 Find out where this coroutine's guard patterns end. This is intended as a part of the tools to measure how much stack something is using:
892
893
 #!C
894
 Coroutine_ClearStackForHWM();
895
 char *before = (char *)Coroutine_GetStackHWM();
896
 // do the thing you want to measure here
897
 char *after = (char *)Coroutine_GetStackHWM();
898
 intptr_t amount_used = before - after;
899
900
 ##### void Coroutine_ClearStackForHWM(void)
901
902
 Fill the unused stack in this coroutine with a guard pattern. This is intended as a part of the tools to measure how much stack something is using:
903
904
 #!C
905
 Coroutine_ClearStackForHWM();
906
 char *before = (char *)Coroutine_GetStackHWM();
907
 // do the thing you want to measure here
908
 char *after = (char *)Coroutine_GetStackHWM();
909
 intptr_t amount_used = before - after;
910
9 months ago
911
 ##### void *Coroutine_GetCStackTop()
9 months ago
912
913
 Return an address which is near to the top of used C stack.
914
9 months ago
915
 ##### void *Coroutine_Chain(Coroutine_Start start, void *value)
9 months ago
916
917
 Run `start` with `value` on a new coroutine, and return its return value. It is expected that `Coroutine_Chain()` will be used when your coroutine is running short of stack - it is not an alternative to `Coroutine_Run()`.
918