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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "fec_private.h"
struct process_info {
int id;
fec_handle *f;
uint8_t *buf;
size_t count;
uint64_t offset;
read_func func;
ssize_t rc;
size_t errors;
};
/* thread function */
static void * __process(void *cookie)
{
process_info *p = static_cast<process_info *>(cookie);
debug("thread %d: [%" PRIu64 ", %" PRIu64 ")", p->id, p->offset,
p->offset + p->count);
p->rc = p->func(p->f, p->buf, p->count, p->offset, &p->errors);
return p;
}
/* launches a maximum number of threads to process a read */
ssize_t process(fec_handle *f, uint8_t *buf, size_t count, uint64_t offset,
read_func func)
{
check(f);
check(buf)
check(func);
if (count == 0) {
return 0;
}
int threads = sysconf(_SC_NPROCESSORS_ONLN);
if (threads < WORK_MIN_THREADS) {
threads = WORK_MIN_THREADS;
} else if (threads > WORK_MAX_THREADS) {
threads = WORK_MAX_THREADS;
}
uint64_t start = (offset / FEC_BLOCKSIZE) * FEC_BLOCKSIZE;
size_t blocks = fec_div_round_up(count, FEC_BLOCKSIZE);
size_t count_per_thread = fec_div_round_up(blocks, threads) * FEC_BLOCKSIZE;
size_t max_threads = fec_div_round_up(count, count_per_thread);
if ((size_t)threads > max_threads) {
threads = (int)max_threads;
}
size_t left = count;
uint64_t pos = offset;
uint64_t end = start + count_per_thread;
debug("%d threads, %zu bytes per thread (total %zu)", threads,
count_per_thread, count);
std::vector<pthread_t> handles;
process_info info[threads];
ssize_t rc = 0;
/* start threads to process queue */
for (int i = 0; i < threads; ++i) {
check(left > 0);
info[i].id = i;
info[i].f = f;
info[i].buf = &buf[pos - offset];
info[i].count = (size_t)(end - pos);
info[i].offset = pos;
info[i].func = func;
info[i].rc = -1;
info[i].errors = 0;
if (info[i].count > left) {
info[i].count = left;
}
pthread_t thread;
if (pthread_create(&thread, NULL, __process, &info[i]) != 0) {
error("failed to create thread: %s", strerror(errno));
rc = -1;
} else {
handles.push_back(thread);
}
pos = end;
end += count_per_thread;
left -= info[i].count;
}
check(left == 0);
ssize_t nread = 0;
/* wait for all threads to complete */
for (auto thread : handles) {
process_info *p = NULL;
if (pthread_join(thread, (void **)&p) != 0) {
error("failed to join thread: %s", strerror(errno));
rc = -1;
} else if (!p || p->rc == -1) {
rc = -1;
} else {
nread += p->rc;
f->errors += p->errors;
}
}
if (rc == -1) {
errno = EIO;
return -1;
}
return nread;
}
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