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/* Thread pool implementation mostly copied from cbs.h */
#include <errno.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <alloc.h>
#include <array.h>
#include <errors.h>
#include <macros.h>
#include "tpool.h"
#include "work.h"
#include <stdio.h>
static int nproc(void);
static void *tpwork(void *);
static pthread_t thread_buffer[32];
extern const char *lquot, *rquot;
int
nproc(void)
{
errno = 0;
/* Grab the number of processors available on the users system. If we can
we query sysconf() but fallback to 1 for systems that don’t support the
sysconf() method. The user can also override this via the GRAB_NPROCS
environment variable, and if that’s invalid then we just issue a
diagnostic and default to 1.
We don’t want to error on an invalid value for GRAB_NPROCS because we
might be running this tool as part of an editor plugin for example where
finding the root cause of your regexp-search failing may not be so
trivial. */
const char *ev = getenv("GRAB_NPROCS");
if (ev != nullptr && *ev != 0) {
const char *endptr;
long n = strtol(ev, (char **)&endptr, 10);
if (errno == 0 && *endptr == 0)
return (int)n;
if (errno != 0)
warn("strtol: %s:", ev);
if (*endptr != 0)
warn("Invalid value for %s%s%s for GRAB_NPROCS", lquot, ev, rquot);
return 1;
}
#ifdef _SC_NPROCESSORS_ONLN
return (int)sysconf(_SC_NPROCESSORS_ONLN);
#else
return 1;
#endif
}
int
tpinit(tpool_t *tp, const char **files, ptrdiff_t filecnt)
{
tp->files = files;
tp->filecnt = filecnt;
tp->tcnt = nproc();
tp->tcnt = MIN(tp->tcnt, filecnt);
tp->wi = 0;
if (tp->tcnt <= 32)
tp->thrds = thread_buffer;
else if ((tp->thrds = malloc(sizeof(*tp->thrds) * tp->tcnt)) == nullptr)
err("malloc:");
/* If for whatever reason some threads fail to be created, we don’t
panic but instead just continue using the threads that were able
to spawn. If all threads fail to spawn we return 0 and the caller
will resort to single-threaded behaviour. */
int n = 0;
for (int i = 0; i < tp->tcnt; i++) {
if ((errno = pthread_create(tp->thrds + n, nullptr, tpwork, tp)) != 0)
warn("failed to create thread:");
else
n++;
}
return n;
}
void
tpfree(tpool_t *tp)
{
for (int i = 0; i < tp->tcnt; i++)
pthread_join(tp->thrds[i], nullptr);
#if DEBUG
if (tp->thrds != thread_buffer)
free(tp->thrds);
#endif
}
void *
tpwork(void *arg)
{
tpool_t *tp = arg;
allocator_t mem = init_heap_allocator(nullptr);
unsigned char *buf = array_new(mem, typeof(*buf), 4096);
for (;;) {
ptrdiff_t i = atomic_fetch_add(&tp->wi, 1);
if (i >= tp->filecnt)
break;
process_file(tp->files[i], &buf);
}
fwrite(buf, 1, array_len(buf), stdout);
#if DEBUG
array_free(buf);
#endif
return nullptr;
}
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