A thread pool manager using the Tcl library thread interface. This is likely duplicating some of the function of that supports the thread pool script interface, but it wasn't clear to me how to access that from C.
tpool.h:
typedef void (*TPoolWork)(void *data);
typedef struct _TPoolThread {
struct _TPool *tp;
Tcl_ThreadId id;
TPoolWork func;
Tcl_Mutex lock;
Tcl_Condition wait;
void *data;
int work;
} TPoolThread;
typedef struct _TPool {
Tcl_Mutex lock;
Tcl_Condition wait;
int next;
int nthread;
TPoolThread *thread;
} TPool;
TPool *TPoolInit(int n);
TPoolThread *TPoolThreadStart(TPool *tp, TPoolWork func, void *data);
TPoolThread *TPoolThreadWair (TPoolThread *t);tpool.c:
/* Simple thread pool manager
John Roll 2012
*/
#include <stdlib.h>
#define TCL_THREADS 1
#include "tcl.h"
#include "tpool.h"
void TPoolWorker(void *data) {
TPoolThread *t = (TPoolThread *) data;
TPool *tp = t->tp;
int i_have_work;
Tcl_MutexLock(&t->lock);
while ( 1 ) {
t->work = 0;
Tcl_ConditionNotify(&t->wait);
Tcl_ConditionWait(&t->wait, &t->lock, NULL /* no timeout */);
if ( t->work ) {
Tcl_MutexUnlock(&t->lock);
t->func(t->data);
Tcl_MutexLock(&t->lock);
t->work = 0;
Tcl_ConditionNotify(&t->wait);
Tcl_MutexLock(&tp->lock);
Tcl_ConditionNotify(&tp->wait);
Tcl_MutexUnlock(&tp->lock);
}
}
}
TPool *TPoolInit(int n) {
int i;
TPool *tp = calloc(sizeof(TPool), 1);
tp->thread = calloc(sizeof(TPoolThread), n);
tp->nthread = n;
for ( i = 0; i < n; i++ ) {
tp->thread[i].work = 1;
tp->thread[i].tp = tp;
Tcl_CreateThread(&tp->thread[i].id, TPoolWorker, &tp->thread[i], TCL_THREAD_STACK_DEFAULT, TCL_THREAD_NOFL
}
for ( i = 0; i < n; i++ ) {
TPoolThread *t = &tp->thread[i];
Tcl_MutexLock(&t->lock);
if ( t->work ) {
Tcl_ConditionWait(&t->wait, &t->lock, NULL /* no timeout */);
}
Tcl_MutexUnlock(&t->lock);
}
return tp;
}
TPoolThread *TPoolThreadStart(TPool *tp, TPoolWork func, void *data) {
int start = tp->next;
Tcl_MutexLock(&tp->lock);
while ( tp->thread[tp->next].work ) { // Find a thread that will work for us.
TPoolThread *t;
tp->next = ++tp->next % tp->nthread;
if ( tp->next == start ) {
Tcl_ConditionWait(&tp->wait, &tp->lock, NULL /* no timeout */);
}
}
Tcl_MutexUnlock(&tp->lock);
{
TPoolThread *t = &tp->thread[tp->next];
Tcl_MutexLock(&t->lock);
t->func = func;
t->data = data;
t->work = 1;
Tcl_ConditionNotify(&t->wait);
Tcl_MutexUnlock(&t->lock);
return t;
}
}
TPoolThreadWait(TPoolThread *t) {
Tcl_MutexLock(&t->lock);
while ( t->work ) {
Tcl_ConditionWait(&t->wait, &t->lock, NULL /* no timeout */);
}
Tcl_MutexUnlock(&t->lock);
}
