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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file contains the implementation of the command buffer helper class.
#include "gpu/command_buffer/client/cmd_buffer_helper.h"
#include "base/logging.h"
#include "base/time/time.h"
#include "gpu/command_buffer/common/command_buffer.h"
#include "gpu/command_buffer/common/trace_event.h"
namespace gpu {
CommandBufferHelper::CommandBufferHelper(CommandBuffer* command_buffer)
: command_buffer_(command_buffer),
ring_buffer_id_(-1),
ring_buffer_size_(0),
entries_(NULL),
total_entry_count_(0),
immediate_entry_count_(0),
token_(0),
put_(0),
last_put_sent_(0),
#if defined(CMD_HELPER_PERIODIC_FLUSH_CHECK)
commands_issued_(0),
#endif
usable_(true),
context_lost_(false),
flush_automatically_(true),
flush_generation_(0) {
}
void CommandBufferHelper::SetAutomaticFlushes(bool enabled) {
flush_automatically_ = enabled;
CalcImmediateEntries(0);
}
bool CommandBufferHelper::IsContextLost() {
if (!context_lost_) {
context_lost_ = error::IsError(command_buffer()->GetLastError());
}
return context_lost_;
}
void CommandBufferHelper::CalcImmediateEntries(int waiting_count) {
DCHECK_GE(waiting_count, 0);
// Check if usable & allocated.
if (!usable() || !HaveRingBuffer()) {
immediate_entry_count_ = 0;
return;
}
// Get maximum safe contiguous entries.
const int32 curr_get = get_offset();
if (curr_get > put_) {
immediate_entry_count_ = curr_get - put_ - 1;
} else {
immediate_entry_count_ =
total_entry_count_ - put_ - (curr_get == 0 ? 1 : 0);
}
// Limit entry count to force early flushing.
if (flush_automatically_) {
int32 limit =
total_entry_count_ /
((curr_get == last_put_sent_) ? kAutoFlushSmall : kAutoFlushBig);
int32 pending =
(put_ + total_entry_count_ - last_put_sent_) % total_entry_count_;
if (pending > 0 && pending >= limit) {
// Time to force flush.
immediate_entry_count_ = 0;
} else {
// Limit remaining entries, but not lower than waiting_count entries to
// prevent deadlock when command size is greater than the flush limit.
limit -= pending;
limit = limit < waiting_count ? waiting_count : limit;
immediate_entry_count_ =
immediate_entry_count_ > limit ? limit : immediate_entry_count_;
}
}
}
bool CommandBufferHelper::AllocateRingBuffer() {
if (!usable()) {
return false;
}
if (HaveRingBuffer()) {
return true;
}
int32 id = -1;
scoped_refptr<Buffer> buffer =
command_buffer_->CreateTransferBuffer(ring_buffer_size_, &id);
if (id < 0) {
ClearUsable();
return false;
}
ring_buffer_ = buffer;
ring_buffer_id_ = id;
command_buffer_->SetGetBuffer(id);
entries_ = static_cast<CommandBufferEntry*>(ring_buffer_->memory());
total_entry_count_ = ring_buffer_size_ / sizeof(CommandBufferEntry);
// Call to SetGetBuffer(id) above resets get and put offsets to 0.
// No need to query it through IPC.
put_ = 0;
CalcImmediateEntries(0);
return true;
}
void CommandBufferHelper::FreeResources() {
if (HaveRingBuffer()) {
command_buffer_->DestroyTransferBuffer(ring_buffer_id_);
ring_buffer_id_ = -1;
CalcImmediateEntries(0);
}
}
void CommandBufferHelper::FreeRingBuffer() {
CHECK((put_ == get_offset()) ||
error::IsError(command_buffer_->GetLastState().error));
FreeResources();
}
bool CommandBufferHelper::Initialize(int32 ring_buffer_size) {
ring_buffer_size_ = ring_buffer_size;
return AllocateRingBuffer();
}
CommandBufferHelper::~CommandBufferHelper() {
FreeResources();
}
bool CommandBufferHelper::WaitForGetOffsetInRange(int32 start, int32 end) {
if (!usable()) {
return false;
}
command_buffer_->WaitForGetOffsetInRange(start, end);
return command_buffer_->GetLastError() == gpu::error::kNoError;
}
void CommandBufferHelper::Flush() {
// Wrap put_ before flush.
if (put_ == total_entry_count_)
put_ = 0;
if (usable() && last_put_sent_ != put_) {
last_flush_time_ = base::TimeTicks::Now();
last_put_sent_ = put_;
command_buffer_->Flush(put_);
++flush_generation_;
CalcImmediateEntries(0);
}
}
#if defined(CMD_HELPER_PERIODIC_FLUSH_CHECK)
void CommandBufferHelper::PeriodicFlushCheck() {
base::TimeTicks current_time = base::TimeTicks::Now();
if (current_time - last_flush_time_ >
base::TimeDelta::FromMicroseconds(kPeriodicFlushDelayInMicroseconds)) {
Flush();
}
}
#endif
// Calls Flush() and then waits until the buffer is empty. Break early if the
// error is set.
bool CommandBufferHelper::Finish() {
TRACE_EVENT0("gpu", "CommandBufferHelper::Finish");
if (!usable()) {
return false;
}
// If there is no work just exit.
if (put_ == get_offset()) {
return true;
}
DCHECK(HaveRingBuffer());
Flush();
if (!WaitForGetOffsetInRange(put_, put_))
return false;
DCHECK_EQ(get_offset(), put_);
CalcImmediateEntries(0);
return true;
}
// Inserts a new token into the command stream. It uses an increasing value
// scheme so that we don't lose tokens (a token has passed if the current token
// value is higher than that token). Calls Finish() if the token value wraps,
// which will be rare.
int32 CommandBufferHelper::InsertToken() {
AllocateRingBuffer();
if (!usable()) {
return token_;
}
DCHECK(HaveRingBuffer());
// Increment token as 31-bit integer. Negative values are used to signal an
// error.
token_ = (token_ + 1) & 0x7FFFFFFF;
cmd::SetToken* cmd = GetCmdSpace<cmd::SetToken>();
if (cmd) {
cmd->Init(token_);
if (token_ == 0) {
TRACE_EVENT0("gpu", "CommandBufferHelper::InsertToken(wrapped)");
// we wrapped
Finish();
DCHECK_EQ(token_, last_token_read());
}
}
return token_;
}
// Waits until the current token value is greater or equal to the value passed
// in argument.
void CommandBufferHelper::WaitForToken(int32 token) {
if (!usable() || !HaveRingBuffer()) {
return;
}
// Return immediately if corresponding InsertToken failed.
if (token < 0)
return;
if (token > token_) return; // we wrapped
if (last_token_read() >= token)
return;
Flush();
command_buffer_->WaitForTokenInRange(token, token_);
}
// Waits for available entries, basically waiting until get >= put + count + 1.
// It actually waits for contiguous entries, so it may need to wrap the buffer
// around, adding a noops. Thus this function may change the value of put_. The
// function will return early if an error occurs, in which case the available
// space may not be available.
void CommandBufferHelper::WaitForAvailableEntries(int32 count) {
AllocateRingBuffer();
if (!usable()) {
return;
}
DCHECK(HaveRingBuffer());
DCHECK(count < total_entry_count_);
if (put_ + count > total_entry_count_) {
// There's not enough room between the current put and the end of the
// buffer, so we need to wrap. We will add noops all the way to the end,
// but we need to make sure get wraps first, actually that get is 1 or
// more (since put will wrap to 0 after we add the noops).
DCHECK_LE(1, put_);
int32 curr_get = get_offset();
if (curr_get > put_ || curr_get == 0) {
TRACE_EVENT0("gpu", "CommandBufferHelper::WaitForAvailableEntries");
Flush();
if (!WaitForGetOffsetInRange(1, put_))
return;
curr_get = get_offset();
DCHECK_LE(curr_get, put_);
DCHECK_NE(0, curr_get);
}
// Insert Noops to fill out the buffer.
int32 num_entries = total_entry_count_ - put_;
while (num_entries > 0) {
int32 num_to_skip = std::min(CommandHeader::kMaxSize, num_entries);
cmd::Noop::Set(&entries_[put_], num_to_skip);
put_ += num_to_skip;
num_entries -= num_to_skip;
}
put_ = 0;
}
// Try to get 'count' entries without flushing.
CalcImmediateEntries(count);
if (immediate_entry_count_ < count) {
// Try again with a shallow Flush().
Flush();
CalcImmediateEntries(count);
if (immediate_entry_count_ < count) {
// Buffer is full. Need to wait for entries.
TRACE_EVENT0("gpu", "CommandBufferHelper::WaitForAvailableEntries1");
if (!WaitForGetOffsetInRange(put_ + count + 1, put_))
return;
CalcImmediateEntries(count);
DCHECK_GE(immediate_entry_count_, count);
}
}
}
} // namespace gpu
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