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