// Copyright 2008 Google Inc. All Rights Reserved.
// 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.
// Thread-safe container of disk blocks
// This file must work with autoconf on its public version,
// so these includes are correct.
#include "disk_blocks.h"
#include <utility>
// BlockData
BlockData::BlockData() : address_(0), size_(0),
references_(0), initialized_(false),
pattern_(NULL) {
pthread_mutex_init(&data_mutex_, NULL);
}
BlockData::~BlockData() {
pthread_mutex_destroy(&data_mutex_);
}
void BlockData::set_initialized() {
pthread_mutex_lock(&data_mutex_);
initialized_ = true;
pthread_mutex_unlock(&data_mutex_);
}
bool BlockData::initialized() const {
pthread_mutex_lock(&data_mutex_);
bool initialized = initialized_;
pthread_mutex_unlock(&data_mutex_);
return initialized;
}
// DiskBlockTable
DiskBlockTable::DiskBlockTable() : sector_size_(0), write_block_size_(0),
device_name_(""), device_sectors_(0),
segment_size_(0), size_(0) {
pthread_mutex_init(&data_mutex_, NULL);
pthread_mutex_init(¶meter_mutex_, NULL);
pthread_cond_init(&data_condition_, NULL);
}
DiskBlockTable::~DiskBlockTable() {
pthread_mutex_destroy(&data_mutex_);
pthread_mutex_destroy(¶meter_mutex_);
pthread_cond_destroy(&data_condition_);
}
// 64-bit non-negative random number generator. Stolen from
// depot/google3/base/tracecontext_unittest.cc.
int64 DiskBlockTable::Random64() {
int64 x = random();
x = (x << 30) ^ random();
x = (x << 30) ^ random();
if (x >= 0)
return x;
else
return -x;
}
uint64 DiskBlockTable::Size() {
pthread_mutex_lock(&data_mutex_);
uint64 size = size_;
pthread_mutex_unlock(&data_mutex_);
return size;
}
void DiskBlockTable::InsertOnStructure(BlockData *block) {
int64 address = block->address();
StorageData *sd = new StorageData();
sd->block = block;
sd->pos = size_;
// Creating new block ...
pthread_mutex_lock(&data_mutex_);
if (pos_to_addr_.size() <= size_) {
pos_to_addr_.insert(pos_to_addr_.end(), address);
} else {
pos_to_addr_[size_] = address;
}
addr_to_block_[address] = sd;
size_++;
pthread_cond_broadcast(&data_condition_);
pthread_mutex_unlock(&data_mutex_);
}
int DiskBlockTable::RemoveBlock(BlockData *block) {
// For write threads, check the reference counter and remove
// it from the structure.
int64 address = block->address();
AddrToBlockMap::iterator it = addr_to_block_.find(address);
int ret = 1;
if (it != addr_to_block_.end()) {
int curr_pos = it->second->pos;
int last_pos = size_ - 1;
AddrToBlockMap::iterator last_it = addr_to_block_.find(
pos_to_addr_[last_pos]);
sat_assert(size_ > 0);
sat_assert(last_it != addr_to_block_.end());
// Everything is fine, removing block from table.
pthread_mutex_lock(&data_mutex_);
pos_to_addr_[curr_pos] = pos_to_addr_[last_pos];
last_it->second->pos = curr_pos;
delete it->second;
addr_to_block_.erase(it);
size_--;
block->DecreaseReferenceCounter();
if (block->GetReferenceCounter() == 0)
delete block;
else if (block->GetReferenceCounter() < 0)
ret = 0;
pthread_cond_broadcast(&data_condition_);
pthread_mutex_unlock(&data_mutex_);
} else {
ret = 0;
}
return ret;
}
int DiskBlockTable::ReleaseBlock(BlockData *block) {
// If caller is a random thread, just check the reference counter.
int ret = 1;
pthread_mutex_lock(&data_mutex_);
int references = block->GetReferenceCounter();
if (references == 1)
delete block;
else if (references > 0)
block->DecreaseReferenceCounter();
else
ret = 0;
pthread_mutex_unlock(&data_mutex_);
return ret;
}
BlockData *DiskBlockTable::GetRandomBlock() {
struct timespec ts;
struct timeval tp;
gettimeofday(&tp, NULL);
ts.tv_sec = tp.tv_sec;
ts.tv_nsec = tp.tv_usec * 1000;
ts.tv_sec += 2; // Wait for 2 seconds.
int result = 0;
pthread_mutex_lock(&data_mutex_);
while (!size_ && result != ETIMEDOUT) {
result = pthread_cond_timedwait(&data_condition_, &data_mutex_, &ts);
}
if (result == ETIMEDOUT) {
pthread_mutex_unlock(&data_mutex_);
return NULL;
} else {
int64 random_number = Random64();
int64 random_pos = random_number % size_;
int64 address = pos_to_addr_[random_pos];
AddrToBlockMap::const_iterator it = addr_to_block_.find(address);
sat_assert(it != addr_to_block_.end());
BlockData *b = it->second->block;
// A block is returned only if its content is written on disk.
if (b->initialized()) {
b->IncreaseReferenceCounter();
} else {
b = NULL;
}
pthread_mutex_unlock(&data_mutex_);
return b;
}
}
void DiskBlockTable::SetParameters(int sector_size,
int write_block_size,
int64 device_sectors,
int64 segment_size,
const string& device_name) {
sat_assert(size_ == 0);
pthread_mutex_lock(¶meter_mutex_);
sector_size_ = sector_size;
write_block_size_ = write_block_size;
device_sectors_ = device_sectors;
segment_size_ = segment_size;
device_name_ = device_name;
pthread_mutex_unlock(¶meter_mutex_);
}
BlockData *DiskBlockTable::GetUnusedBlock(int64 segment) {
int64 sector = 0;
BlockData *block = new BlockData();
bool good_sequence = false;
if (block == NULL) {
logprintf(0, "Process Error: Unable to allocate memory "
"for sector data for disk %s.\n", device_name_.c_str());
return NULL;
}
pthread_mutex_lock(¶meter_mutex_);
sat_assert(device_sectors_ != 0);
// Align the first sector with the beginning of a write block
int num_sectors = write_block_size_ / sector_size_;
for (int i = 0; i < kBlockRetry && !good_sequence; i++) {
good_sequence = true;
// Use the entire disk or a small segment of the disk to allocate the first
// sector in the block from.
if (segment_size_ == -1) {
sector = (Random64() & 0x7FFFFFFFFFFFFFFFLL) % (
device_sectors_ / num_sectors);
sector *= num_sectors;
} else {
sector = (Random64() & 0x7FFFFFFFFFFFFFFFLL) % (
segment_size_ / num_sectors);
sector *= num_sectors;
sector += segment * segment_size_;
// Make sure the block is within the segment.
if (sector + num_sectors > (segment + 1) * segment_size_) {
good_sequence = false;
continue;
}
}
// Make sure the entire block is in range.
if (sector + num_sectors > device_sectors_) {
good_sequence = false;
continue;
}
// Check to see if the block is free. Since the blocks are
// now aligned to the write_block_size, it is not necessary
// to check each sector, just the first block (a sector
// overlap will never occur).
pthread_mutex_lock(&data_mutex_);
if (addr_to_block_.find(sector) != addr_to_block_.end()) {
good_sequence = false;
}
pthread_mutex_unlock(&data_mutex_);
}
if (good_sequence) {
block->set_address(sector);
block->set_size(write_block_size_);
block->IncreaseReferenceCounter();
InsertOnStructure(block);
} else {
// No contiguous sequence of num_sectors sectors was found within
// kBlockRetry iterations so return an error value.
delete block;
block = NULL;
}
pthread_mutex_unlock(¶meter_mutex_);
return block;
}