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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 COMMAND_SIZE 2
     22 #define NUM_COMMANDS 50
     23 #define BUFFER_SIZE ((NUM_COMMANDS * COMMAND_SIZE) + 1)
     24 
     25 /**
     26  * DisplayListLogBuffer is a utility class which logs the most recent display
     27  * list operations in a circular buffer. The log is process-wide, because we
     28  * only care about the most recent operations, not the operations on a per-window
     29  * basis for a given activity. The purpose of the log is to provide more debugging
     30  * information in a bug report, by telling us not just where a process hung (which
     31  * generally is just reported as a stack trace at the Java level) or crashed, but
     32  * also what happened immediately before that hang or crash. This may help track down
     33  * problems in the native rendering code or driver interaction related to the display
     34  * list operations that led up to the hang or crash.
     35  *
     36  * The log is implemented as a circular buffer for both space and performance
     37  * reasons - we only care about the last several operations to give us context
     38  * leading up to the problem, and we don't want to constantly copy data around or do
     39  * additional mallocs to keep the most recent operations logged. Only numbers are
     40  * logged to make the operation fast. If and when the log is output, we process this
     41  * data into meaningful strings.
     42  *
     43  * There is an assumption about the format of the command (currently 2 ints: the
     44  * opcode and the nesting level). If the type of information logged changes (for example,
     45  * we may want to save a timestamp), then the size of the buffer and the way the
     46  * information is recorded in writeCommand() should change to suit.
     47  */
     48 
     49 namespace android {
     50 
     51 #ifdef USE_OPENGL_RENDERER
     52 using namespace uirenderer;
     53 ANDROID_SINGLETON_STATIC_INSTANCE(DisplayListLogBuffer);
     54 #endif
     55 
     56 namespace uirenderer {
     57 
     58 
     59 DisplayListLogBuffer::DisplayListLogBuffer() {
     60     mBufferFirst = (int*) malloc(BUFFER_SIZE * sizeof(int));
     61     mStart = mBufferFirst;
     62     mBufferLast = mBufferFirst + BUFFER_SIZE - 1;
     63     mEnd = mStart;
     64 }
     65 
     66 DisplayListLogBuffer::~DisplayListLogBuffer() {
     67     free(mBufferFirst);
     68 }
     69 
     70 /**
     71  * Called from DisplayListRenderer to output the current buffer into the
     72  * specified FILE. This only happens in a dumpsys/bugreport operation.
     73  */
     74 void DisplayListLogBuffer::outputCommands(FILE *file, const char* opNames[])
     75 {
     76     int *tmpBufferPtr = mStart;
     77     while (true) {
     78         if (tmpBufferPtr == mEnd) {
     79             break;
     80         }
     81         int level = *tmpBufferPtr++;
     82         if (tmpBufferPtr > mBufferLast) {
     83             tmpBufferPtr = mBufferFirst;
     84         }
     85         int op = *tmpBufferPtr++;
     86         if (tmpBufferPtr > mBufferLast) {
     87             tmpBufferPtr = mBufferFirst;
     88         }
     89         uint32_t count = (level + 1) * 2;
     90         char indent[count + 1];
     91         for (uint32_t i = 0; i < count; i++) {
     92             indent[i] = ' ';
     93         }
     94         indent[count] = '\0';
     95         fprintf(file, "%s%s\n", indent, opNames[op]);
     96     }
     97 }
     98 
     99 void DisplayListLogBuffer::writeCommand(int level, int op) {
    100     writeInt(level);
    101     writeInt(op);
    102 }
    103 
    104 /**
    105  * Store the given value in the buffer and increment/wrap the mEnd
    106  * and mStart values as appropriate.
    107  */
    108 void DisplayListLogBuffer::writeInt(int value) {
    109     *((int*)mEnd) = value;
    110     if (mEnd == mBufferLast) {
    111         mEnd = mBufferFirst;
    112     } else {
    113         mEnd++;
    114     }
    115     if (mEnd == mStart) {
    116         mStart++;
    117         if (mStart > mBufferLast) {
    118             mStart = mBufferFirst;
    119         }
    120     }
    121 }
    122 
    123 }; // namespace uirenderer
    124 }; // namespace android
    125