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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "DisplayListLogBuffer.h"
     18 
     19 // BUFFER_SIZE size must be one more than a multiple of COMMAND_SIZE to ensure
     20 // that mStart always points at the next command, not just the next item
     21 #define NUM_COMMANDS 50
     22 #define BUFFER_SIZE ((NUM_COMMANDS) + 1)
     23 
     24 /**
     25  * DisplayListLogBuffer is a utility class which logs the most recent display
     26  * list operations in a circular buffer. The log is process-wide, because we
     27  * only care about the most recent operations, not the operations on a per-window
     28  * basis for a given activity. The purpose of the log is to provide more debugging
     29  * information in a bug report, by telling us not just where a process hung (which
     30  * generally is just reported as a stack trace at the Java level) or crashed, but
     31  * also what happened immediately before that hang or crash. This may help track down
     32  * problems in the native rendering code or driver interaction related to the display
     33  * list operations that led up to the hang or crash.
     34  *
     35  * The log is implemented as a circular buffer for both space and performance
     36  * reasons - we only care about the last several operations to give us context
     37  * leading up to the problem, and we don't want to constantly copy data around or do
     38  * additional mallocs to keep the most recent operations logged. Only numbers are
     39  * logged to make the operation fast. If and when the log is output, we process this
     40  * data into meaningful strings.
     41  *
     42  * There is an assumption about the format of the command (currently 2 ints: the
     43  * opcode and the nesting level). If the type of information logged changes (for example,
     44  * we may want to save a timestamp), then the size of the buffer and the way the
     45  * information is recorded in writeCommand() should change to suit.
     46  */
     47 
     48 namespace android {
     49 
     50 #ifdef USE_OPENGL_RENDERER
     51 using namespace uirenderer;
     52 ANDROID_SINGLETON_STATIC_INSTANCE(DisplayListLogBuffer);
     53 #endif
     54 
     55 namespace uirenderer {
     56 
     57 
     58 DisplayListLogBuffer::DisplayListLogBuffer() {
     59     mBufferFirst = (OpLog*) malloc(BUFFER_SIZE * sizeof(OpLog));
     60     mStart = mBufferFirst;
     61     mBufferLast = mBufferFirst + BUFFER_SIZE - 1;
     62     mEnd = mStart;
     63 }
     64 
     65 DisplayListLogBuffer::~DisplayListLogBuffer() {
     66     free(mBufferFirst);
     67 }
     68 
     69 /**
     70  * Called from DisplayListRenderer to output the current buffer into the
     71  * specified FILE. This only happens in a dumpsys/bugreport operation.
     72  */
     73 void DisplayListLogBuffer::outputCommands(FILE *file)
     74 {
     75     OpLog* tmpBufferPtr = mStart;
     76     while (true) {
     77         if (tmpBufferPtr == mEnd) {
     78             break;
     79         }
     80 
     81         fprintf(file, "%*s%s\n", 2 * tmpBufferPtr->level, "", tmpBufferPtr->label);
     82 
     83         OpLog* nextOp = tmpBufferPtr++;
     84         if (tmpBufferPtr > mBufferLast) {
     85             tmpBufferPtr = mBufferFirst;
     86         }
     87     }
     88 }
     89 
     90 /**
     91  * Store the given level and label in the buffer and increment/wrap the mEnd
     92  * and mStart values as appropriate. Label should point to static memory.
     93  */
     94 void DisplayListLogBuffer::writeCommand(int level, const char* label) {
     95     mEnd->level = level;
     96     mEnd->label = label;
     97 
     98     if (mEnd == mBufferLast) {
     99         mEnd = mBufferFirst;
    100     } else {
    101         mEnd++;
    102     }
    103     if (mEnd == mStart) {
    104         mStart++;
    105         if (mStart > mBufferLast) {
    106             mStart = mBufferFirst;
    107         }
    108     }
    109 }
    110 
    111 }; // namespace uirenderer
    112 }; // namespace android
    113