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Edit File: pack-ops.js

"use strict";

var sha1 = require('git-sha1');
var applyDelta = require('../lib/apply-delta.js');
var codec = require('../lib/object-codec.js');
var decodePack = require('../lib/pack-codec.js').decodePack;
var encodePack = require('../lib/pack-codec.js').encodePack;
var makeChannel = require('culvert');

module.exports = function (repo) {
  // packChannel is a writable culvert channel {put,drain} containing raw packfile binary data
  // opts can contain "onProgress" or "onError" hook functions.
  // callback will be called with a list of all unpacked hashes on success.
  repo.unpack = unpack; // (packChannel, opts) => hashes

// hashes is an array of hashes to pack
  // packChannel will be a readable culvert channel {take} containing raw packfile binary data
  repo.pack = pack;     // (hashes, opts) => packChannel
};

function unpack(packChannel, opts, callback) {
  /*jshint validthis:true*/
  if (!callback) return unpack.bind(this, packChannel, opts);

packChannel = applyParser(packChannel, decodePack, callback);

var repo = this;

var version, num, numDeltas = 0, count = 0, countDeltas = 0;
  var done, startDeltaProgress = false;

// hashes keyed by offset for ofs-delta resolving
  var hashes = {};
  // key is hash, boolean is cached "has" value of true or false
  var has = {};
  // key is hash we're waiting for, value is array of items that are waiting.
  var pending = {};

return packChannel.take(onStats);

function onDone(err) {
    if (done) return;
    done = true;
    if (err) return callback(err);
    return callback(null, values(hashes));
  }

function onStats(err, stats) {
    if (err) return onDone(err);
    version = stats.version;
    num = stats.num;
    packChannel.take(onRead);
  }

function objectProgress(more) {
    if (!more) startDeltaProgress = true;
    var percent = Math.round(count / num * 100);
    return opts.onProgress("Receiving objects: " + percent + "% (" + (count++) + "/" + num + ")   " + (more ? "\r" : "\n"));
  }

function deltaProgress(more) {
    if (!startDeltaProgress) return;
    var percent = Math.round(countDeltas / numDeltas * 100);
    return opts.onProgress("Applying deltas: " + percent + "% (" + (countDeltas++) + "/" + numDeltas + ")   " + (more ? "\r" : "\n"));
  }

function resolveDelta(item) {
    if (opts.onProgress) deltaProgress();
    return repo.loadRaw(item.ref, function (err, buffer) {
      if (err) return onDone(err);
      if (!buffer) return onDone(new Error("Missing base image at " + item.ref));
      var target = codec.deframe(buffer);
      item.type = target.type;
      item.body = applyDelta(item.body, target.body);
      return saveValue(item);
    });
  }

function checkDelta(item) {
    var hasTarget = has[item.ref];
    if (hasTarget === true) return resolveDelta(item);
    if (hasTarget === false) return enqueueDelta(item);
    return repo.hasHash(item.ref, function (err, value) {
      if (err) return onDone(err);
      has[item.ref] = value;
      if (value) return resolveDelta(item);
      return enqueueDelta(item);
    });
  }

function onSave(err) {
    if (err) return callback(err);
    packChannel.take(onRead);
  }

function enqueueDelta(item) {
    var list = pending[item.ref];
    if (!list) pending[item.ref] = [item];
    else list.push(item);
    packChannel.take(onRead);
  }

}

// TODO: Implement delta refs to reduce stream size
function pack(hashes, opts, callback) {
  /*jshint validthis:true*/
  if (!callback) return pack.bind(this, hashes, opts);
  var repo = this;
  var i = 0, first = true, done = false;
  return callback(null, applyParser({ take: take }, encodePack));

function readFirst(callback) {
    first = false;
    callback(null, {num: hashes.length});
  }
}

function values(object) {
  var keys = Object.keys(object);
  var length = keys.length;
  var out = new Array(length);
  for (var i = 0; i < length; i++) {
    out[i] = object[keys[i]];
  }
  return out;
}

function applyParser(stream, parser, onError) {
  var extra = makeChannel();
  extra.put = parser(extra.put);
  stream.take(onData);

function onDrain(err) {
    if (err) return onError(err);
    stream.take(onData);
  }

return { take: extra.take };
}

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