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/*
* Copyright (C) 2020 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 "SerializedFlushToState.h"
#include <limits>
#include <android-base/logging.h>
SerializedFlushToState::SerializedFlushToState(uint64_t start, LogMask log_mask,
std::list<SerializedLogChunk>* logs)
: FlushToState(start, log_mask), logs_(logs) {
log_id_for_each(i) {
if (((1 << i) & log_mask) == 0) {
continue;
}
logs_needed_from_next_position_[i] = true;
}
}
SerializedFlushToState::~SerializedFlushToState() {
log_id_for_each(i) {
if (log_positions_[i]) {
log_positions_[i]->buffer_it->DetachReader(this);
}
}
}
void SerializedFlushToState::CreateLogPosition(log_id_t log_id) {
CHECK(!logs_[log_id].empty());
LogPosition log_position;
auto it = logs_[log_id].begin();
while (it != logs_[log_id].end() && start() > it->highest_sequence_number()) {
++it;
}
if (it == logs_[log_id].end()) {
--it;
}
it->AttachReader(this);
log_position.buffer_it = it;
// Find the offset of the first log with sequence number >= start().
int read_offset = 0;
while (read_offset < it->write_offset()) {
const auto* entry = it->log_entry(read_offset);
if (entry->sequence() >= start()) {
break;
}
read_offset += entry->total_len();
}
log_position.read_offset = read_offset;
log_positions_[log_id].emplace(log_position);
}
void SerializedFlushToState::UpdateLogsNeeded(log_id_t log_id) {
auto& buffer_it = log_positions_[log_id]->buffer_it;
auto read_offset = log_positions_[log_id]->read_offset;
// If there is another log to read in this buffer, let it be read.
if (read_offset < buffer_it->write_offset()) {
logs_needed_from_next_position_[log_id] = false;
} else if (read_offset == buffer_it->write_offset()) {
// If there are no more logs to read in this buffer and it's the last buffer, then
// set logs_needed_from_next_position_ to wait until more logs get logged.
if (buffer_it == std::prev(logs_[log_id].end())) {
logs_needed_from_next_position_[log_id] = true;
} else {
// Otherwise, if there is another buffer piece, move to that and do the same check.
buffer_it->DetachReader(this);
++buffer_it;
buffer_it->AttachReader(this);
log_positions_[log_id]->read_offset = 0;
if (buffer_it->write_offset() == 0) {
logs_needed_from_next_position_[log_id] = true;
} else {
logs_needed_from_next_position_[log_id] = false;
}
}
} else {
// read_offset > buffer_it->write_offset() should never happen.
LOG(FATAL) << "read_offset (" << read_offset << ") > buffer_it->write_offset() ("
<< buffer_it->write_offset() << ")";
}
}
void SerializedFlushToState::CheckForNewLogs() {
log_id_for_each(i) {
if (!logs_needed_from_next_position_[i]) {
continue;
}
if (!log_positions_[i]) {
if (logs_[i].empty()) {
continue;
}
CreateLogPosition(i);
}
UpdateLogsNeeded(i);
}
}
bool SerializedFlushToState::HasUnreadLogs() {
CheckForNewLogs();
log_id_for_each(i) {
if (log_positions_[i] && !logs_needed_from_next_position_[i]) {
return true;
}
}
return false;
}
LogWithId SerializedFlushToState::PopNextUnreadLog() {
uint64_t min_sequence = std::numeric_limits<uint64_t>::max();
log_id_t log_id;
const SerializedLogEntry* entry = nullptr;
log_id_for_each(i) {
if (!log_positions_[i] || logs_needed_from_next_position_[i]) {
continue;
}
if (log_positions_[i]->log_entry()->sequence() < min_sequence) {
log_id = i;
entry = log_positions_[i]->log_entry();
min_sequence = entry->sequence();
}
}
CHECK_NE(nullptr, entry);
log_positions_[log_id]->read_offset += entry->total_len();
logs_needed_from_next_position_[log_id] = true;
return {log_id, entry};
}
void SerializedFlushToState::Prune(log_id_t log_id) {
CHECK(log_positions_[log_id].has_value());
// Decrease the ref count since we're deleting our reference.
log_positions_[log_id]->buffer_it->DetachReader(this);
// Delete in the reference.
log_positions_[log_id].reset();
// Finally set logs_needed_from_next_position_, so CheckForNewLogs() will re-create the
// log_position_ object during the next read.
logs_needed_from_next_position_[log_id] = true;
}
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