logreader.js

// Copyright 2011 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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/**
 * @fileoverview Log Reader is used to process log file produced by V8.
 */


/**
 * Base class for processing log files.
 *
 * @param {Array.<Object>} dispatchTable A table used for parsing and processing
 *     log records.
 * @param {boolean} timedRange Ignore ticks outside timed range.
 * @param {boolean} pairwiseTimedRange Ignore ticks outside pairs of timer
 *     markers.
 * @constructor
 */
function LogReader(dispatchTable, timedRange, pairwiseTimedRange) {
  /**
   * @type {Array.<Object>}
   */
  this.dispatchTable_ = dispatchTable;

  /**
   * @type {boolean}
   */
  this.timedRange_ = timedRange;

  /**
   * @type {boolean}
   */
  this.pairwiseTimedRange_ = pairwiseTimedRange;
  if (pairwiseTimedRange) {
    this.timedRange_ = true;
  }

  /**
   * Current line.
   * @type {number}
   */
  this.lineNum_ = 0;

  /**
   * CSV lines parser.
   * @type {CsvParser}
   */
  this.csvParser_ = new CsvParser();

  /**
   * Keeps track of whether we've seen a "current-time" tick yet.
   * @type {boolean}
   */
  this.hasSeenTimerMarker_ = false;

  /**
   * List of log lines seen since last "current-time" tick.
   * @type {Array.<String>}
   */
  this.logLinesSinceLastTimerMarker_ = [];
};


/**
 * Used for printing error messages.
 *
 * @param {string} str Error message.
 */
LogReader.prototype.printError = function(str) {
  // Do nothing.
};


/**
 * Processes a portion of V8 profiler event log.
 *
 * @param {string} chunk A portion of log.
 */
LogReader.prototype.processLogChunk = function(chunk) {
  this.processLog_(chunk.split('\n'));
};


/**
 * Processes a line of V8 profiler event log.
 *
 * @param {string} line A line of log.
 */
LogReader.prototype.processLogLine = function(line) {
  if (!this.timedRange_) {
    this.processLogLine_(line);
    return;
  }
  if (line.startsWith("current-time")) {
    if (this.hasSeenTimerMarker_) {
      this.processLog_(this.logLinesSinceLastTimerMarker_);
      this.logLinesSinceLastTimerMarker_ = [];
      // In pairwise mode, a "current-time" line ends the timed range.
      if (this.pairwiseTimedRange_) {
        this.hasSeenTimerMarker_ = false;
      }
    } else {
      this.hasSeenTimerMarker_ = true;
    }
  } else {
    if (this.hasSeenTimerMarker_) {
      this.logLinesSinceLastTimerMarker_.push(line);
    } else if (!line.startsWith("tick")) {
      this.processLogLine_(line);
    }
  }
};


/**
 * Processes stack record.
 *
 * @param {number} pc Program counter.
 * @param {number} func JS Function.
 * @param {Array.<string>} stack String representation of a stack.
 * @return {Array.<number>} Processed stack.
 */
LogReader.prototype.processStack = function(pc, func, stack) {
  var fullStack = func ? [pc, func] : [pc];
  var prevFrame = pc;
  for (var i = 0, n = stack.length; i < n; ++i) {
    var frame = stack[i];
    var firstChar = frame.charAt(0);
    if (firstChar == '+' || firstChar == '-') {
      // An offset from the previous frame.
      prevFrame += parseInt(frame, 16);
      fullStack.push(prevFrame);
    // Filter out possible 'overflow' string.
    } else if (firstChar != 'o') {
      fullStack.push(parseInt(frame, 16));
    } else {
      this.printError("dropping: " + frame);
    }
  }
  return fullStack;
};


/**
 * Returns whether a particular dispatch must be skipped.
 *
 * @param {!Object} dispatch Dispatch record.
 * @return {boolean} True if dispatch must be skipped.
 */
LogReader.prototype.skipDispatch = function(dispatch) {
  return false;
};

// Parses dummy variable for readability;
const parseString = 'parse-string';
const parseVarArgs = 'parse-var-args';

/**
 * Does a dispatch of a log record.
 *
 * @param {Array.<string>} fields Log record.
 * @private
 */
LogReader.prototype.dispatchLogRow_ = function(fields) {
  // Obtain the dispatch.
  var command = fields[0];
  var dispatch = this.dispatchTable_[command];
  if (dispatch === undefined) return;

  if (dispatch === null || this.skipDispatch(dispatch)) {
    return;
  }

  // Parse fields.
  var parsedFields = [];
  for (var i = 0; i < dispatch.parsers.length; ++i) {
    var parser = dispatch.parsers[i];
    if (parser === parseString) {
      parsedFields.push(fields[1 + i]);
    } else if (typeof parser == 'function') {
      parsedFields.push(parser(fields[1 + i]));
    } else if (parser === parseVarArgs) {
      // var-args
      parsedFields.push(fields.slice(1 + i));
      break;
    } else {
      throw new Error("Invalid log field parser: " + parser);
    }
  }

  // Run the processor.
  dispatch.processor.apply(this, parsedFields);
};


/**
 * Processes log lines.
 *
 * @param {Array.<string>} lines Log lines.
 * @private
 */
LogReader.prototype.processLog_ = function(lines) {
  for (var i = 0, n = lines.length; i < n; ++i) {
    this.processLogLine_(lines[i]);
  }
}

/**
 * Processes a single log line.
 *
 * @param {String} a log line
 * @private
 */
LogReader.prototype.processLogLine_ = function(line) {
  if (line.length > 0) {
    try {
      var fields = this.csvParser_.parseLine(line);
      this.dispatchLogRow_(fields);
    } catch (e) {
      this.printError('line ' + (this.lineNum_ + 1) + ': ' + (e.message || e));
    }
  }
  this.lineNum_++;
};