blob: 45aaccac7abeed8111ee5c68a2a46e78ecef870c [file] [log] [blame]
* Copyright (C) 2011 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "DisplayListLogBuffer.h"
// BUFFER_SIZE size must be one more than a multiple of COMMAND_SIZE to ensure
// that mStart always points at the next command, not just the next item
#define NUM_COMMANDS 50
* DisplayListLogBuffer is a utility class which logs the most recent display
* list operations in a circular buffer. The log is process-wide, because we
* only care about the most recent operations, not the operations on a per-window
* basis for a given activity. The purpose of the log is to provide more debugging
* information in a bug report, by telling us not just where a process hung (which
* generally is just reported as a stack trace at the Java level) or crashed, but
* also what happened immediately before that hang or crash. This may help track down
* problems in the native rendering code or driver interaction related to the display
* list operations that led up to the hang or crash.
* The log is implemented as a circular buffer for both space and performance
* reasons - we only care about the last several operations to give us context
* leading up to the problem, and we don't want to constantly copy data around or do
* additional mallocs to keep the most recent operations logged. Only numbers are
* logged to make the operation fast. If and when the log is output, we process this
* data into meaningful strings.
* There is an assumption about the format of the command (currently 2 ints: the
* opcode and the nesting level). If the type of information logged changes (for example,
* we may want to save a timestamp), then the size of the buffer and the way the
* information is recorded in writeCommand() should change to suit.
namespace android {
using namespace uirenderer;
namespace uirenderer {
DisplayListLogBuffer::DisplayListLogBuffer() {
mBufferFirst = (OpLog*) malloc(BUFFER_SIZE * sizeof(OpLog));
mStart = mBufferFirst;
mBufferLast = mBufferFirst + BUFFER_SIZE - 1;
mEnd = mStart;
DisplayListLogBuffer::~DisplayListLogBuffer() {
* Called from DisplayListRenderer to output the current buffer into the
* specified FILE. This only happens in a dumpsys/bugreport operation.
void DisplayListLogBuffer::outputCommands(FILE *file)
OpLog* tmpBufferPtr = mStart;
while (true) {
if (tmpBufferPtr == mEnd) {
fprintf(file, "%*s%s\n", 2 * tmpBufferPtr->level, "", tmpBufferPtr->label);
OpLog* nextOp = tmpBufferPtr++;
if (tmpBufferPtr > mBufferLast) {
tmpBufferPtr = mBufferFirst;
* Store the given level and label in the buffer and increment/wrap the mEnd
* and mStart values as appropriate. Label should point to static memory.
void DisplayListLogBuffer::writeCommand(int level, const char* label) {
mEnd->level = level;
mEnd->label = label;
if (mEnd == mBufferLast) {
mEnd = mBufferFirst;
} else {
if (mEnd == mStart) {
if (mStart > mBufferLast) {
mStart = mBufferFirst;
}; // namespace uirenderer
}; // namespace android