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/*
* Copyright (C) 2014 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 "LogReaderThread.h"
#include <errno.h>
#include <string.h>
#include <sys/prctl.h>
#include <thread>
#include "LogBuffer.h"
#include "LogReaderList.h"
#include "SerializedFlushToState.h"
LogReaderThread::LogReaderThread(LogBuffer* log_buffer, LogReaderList* reader_list,
std::unique_ptr<LogWriter> writer, bool non_block,
unsigned long tail, LogMask log_mask, pid_t pid,
log_time start_time, uint64_t start,
std::chrono::steady_clock::time_point deadline)
: log_buffer_(log_buffer),
reader_list_(reader_list),
writer_(std::move(writer)),
pid_(pid),
tail_(tail),
count_(0),
index_(0),
start_time_(start_time),
deadline_(deadline),
non_block_(non_block) {
CleanSkip();
flush_to_state_ = log_buffer_->CreateFlushToState(start, log_mask);
}
void LogReaderThread::Run() {
auto thread = std::thread{&LogReaderThread::ThreadFunction, this};
thread.detach();
}
void LogReaderThread::ThreadFunction() {
prctl(PR_SET_NAME, "logd.reader.per");
auto lock = std::unique_lock{logd_lock};
auto lock_assertion = android::base::ScopedLockAssertion{logd_lock};
while (!release_) {
if (deadline_.time_since_epoch().count() != 0) {
if (thread_triggered_condition_.wait_until(lock, deadline_) ==
std::cv_status::timeout) {
deadline_ = {};
}
if (release_) {
break;
}
}
if (tail_) {
auto first_pass_state = log_buffer_->CreateFlushToState(flush_to_state_->start(),
flush_to_state_->log_mask());
log_buffer_->FlushTo(writer_.get(), *first_pass_state,
[this](log_id_t log_id, pid_t pid, uint64_t sequence,
log_time realtime) REQUIRES(logd_lock) {
return FilterFirstPass(log_id, pid, sequence, realtime);
});
}
bool flush_success = log_buffer_->FlushTo(
writer_.get(), *flush_to_state_,
[this](log_id_t log_id, pid_t pid, uint64_t sequence, log_time realtime) REQUIRES(
logd_lock) { return FilterSecondPass(log_id, pid, sequence, realtime); });
// We only ignore entries before the original start time for the first flushTo(), if we
// get entries after this first flush before the original start time, then the client
// wouldn't have seen them.
// Note: this is still racy and may skip out of order events that came in since the last
// time the client disconnected and then reconnected with the new start time. The long term
// solution here is that clients must request events since a specific sequence number.
start_time_.tv_sec = 0;
start_time_.tv_nsec = 0;
if (!flush_success) {
break;
}
if (non_block_ || release_) {
break;
}
CleanSkip();
if (deadline_.time_since_epoch().count() == 0) {
thread_triggered_condition_.wait(lock);
}
}
writer_->Release();
reader_list_->RemoveRunningThread(this);
}
// A first pass to count the number of elements
FilterResult LogReaderThread::FilterFirstPass(log_id_t, pid_t pid, uint64_t, log_time realtime) {
if ((!pid_ || pid_ == pid) && (start_time_ == log_time::EPOCH || start_time_ <= realtime)) {
++count_;
}
return FilterResult::kSkip;
}
// A second pass to send the selected elements
FilterResult LogReaderThread::FilterSecondPass(log_id_t log_id, pid_t pid, uint64_t,
log_time realtime) {
if (skip_ahead_[log_id]) {
skip_ahead_[log_id]--;
return FilterResult::kSkip;
}
// Truncate to close race between first and second pass
if (non_block_ && tail_ && index_ >= count_) {
return FilterResult::kStop;
}
if (pid_ && pid_ != pid) {
return FilterResult::kSkip;
}
if (start_time_ != log_time::EPOCH && realtime <= start_time_) {
return FilterResult::kSkip;
}
if (release_) {
return FilterResult::kStop;
}
if (!tail_) {
goto ok;
}
++index_;
if (count_ > tail_ && index_ <= (count_ - tail_)) {
return FilterResult::kSkip;
}
if (!non_block_) {
tail_ = 0;
}
ok:
if (!skip_ahead_[log_id]) {
return FilterResult::kWrite;
}
return FilterResult::kSkip;
}
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