fdboost
Version:
Performance enhanced utilities for FoundationDB
380 lines (339 loc) • 13.2 kB
JavaScript
(function() {
var EventEmitter, resolveKey,
__hasProp = {}.hasOwnProperty,
__extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };
EventEmitter = require('events').EventEmitter;
resolveKey = function(k) {
if (k) {
if (k.key) {
if (typeof k.key === 'function') {
return k.key();
} else {
return k.key;
}
} else if (k.rawPrefix) {
return k.rawPrefix;
} else {
return k;
}
}
};
/**
* Get a Reader class to perform a range read operation over the database
* @method
* @param {object} FDBBoost FDBBoost instance.
* @return {Reader} Reader
*/
module.exports = function(fdb, debug) {
var RangeReader, db, iterate, transactionalIterate;
db = fdb.open();
/**
* The callback format for the iterate method
* @callback iterateCallback
* @param {Error} error An error instance representing the error during the execution.
* @param {Result} result A Result value on completion of the iteration.
*/
/**
* Iterate over the range results
* @method
* @param {object} tr Transaction.
* @param {object} reader RangeReader instance.
* @param {string} iteratorType batch|each|array.
* @param {iterateCallback} callback Callback.
* @fires RangeReader#data
* @return {undefined}
*/
iterate = function(tr, reader, iteratorType, callback) {
var getIteratorCallback;
debug(function(writer) {
return writer.buffer('iteratorType', iteratorType);
});
getIteratorCallback = function(err, iterator) {
if (err) {
callback(err);
} else {
debug(function(writer) {
return writer.log('iterate');
});
switch (iteratorType) {
case 'array':
reader.toArray(iterator, callback);
break;
case 'batch':
reader.forEachBatch(iterator, callback);
break;
case 'each':
reader.forEach(iterator, callback);
}
}
};
reader.getIterator(tr, getIteratorCallback);
};
transactionalIterate = fdb.transactional(iterate);
fdb.RangeReader = RangeReader = (function(_super) {
__extends(RangeReader, _super);
/**
* Creates a new Reader instance
* @class
* @param {object} options Settings.
* @param {(Buffer|fdb.KeySelector)} [options.begin] First key in the reader range.
* @param {(Buffer|fdb.KeySelector)}} [options.end=undefined] Last key in the reader range.
* @param {number} [options.limit=undefined] Only the first limit keys (and their values) in the range will be returned.
* @param {boolean} [options.reverse=undefined] Specified if the keys in the range will be returned in reverse order
* @param {(iterator|want_all|small|medium|large|serial|exact)} [options.streamingMode=undefined] fdb.streamingMode property that permits the API client to customize performance tradeoff by providing extra information about how the iterator will be used.
* @param {boolean} [options.nonTransactional=false] Reset transaction on expiry and start.
* @param {boolean} [options.snapshot=false] Defines whether range reads should be snapshot reads.
* @property {array} instances Collection of Document Layer db instances.
* @property {number} index Current index of the instances collection.
* @property {(Buffer|fdb.KeySelector)}} begin First key in the reader range.
* @property {(Buffer|fdb.KeySelector)}} end Last key in the reader range.
* @property {Buffer} marker Marker key for transaction expiration continuation point.
* @property {number} limit Only the first limit keys (and their values) in the range will be returned.
* @property {boolean} reverse Specified if the keys in the range will be returned in reverse order
* @property {(iterator|want_all|small|medium|large|serial|exact)} streamingMode fdb.streamingMode property that permits the API client to customize performance tradeoff by providing extra information about how the iterator will be used.
* @property {boolean} nonTransactional Reset transaction on expiry and start.
* @property {boolean} snapshot Defines whether range reads should be snapshot reads.
* @return {Reader} a Reader instance.
*/
function RangeReader(options) {
RangeReader.__super__.constructor.call(this);
this.begin = options.begin;
this.end = options.end;
this.marker = null;
this.limit = options.limit;
this.reverse = options.reverse;
this.streamingMode = options.streamingMode;
this.nonTransactional = options.nonTransactional || false;
this.snapshot = options.snapshot || false;
debug(function(writer) {
if (options.begin) {
writer.buffer('begin', resolveKey(options.begin).toString('utf8'));
}
if (options.end) {
writer.buffer('end', resolveKey(options.end).toString('utf8'));
}
writer.buffer('limit', options.limit);
writer.buffer('reverse', options.reverse);
writer.buffer('streamingMode', options.streamingMode);
writer.buffer('nonTransactional', options.nonTransactional);
return writer.buffer('snapshot', options.snapshot);
});
this.on('data', (function(_this) {
return function(data) {
var kv, _i, _len;
if (data instanceof Array) {
for (_i = 0, _len = data.length; _i < _len; _i++) {
kv = data[_i];
_this.marker = kv.key;
}
} else {
_this.marker = data.key;
}
};
})(this));
}
/**
* The callback format for the getLastKey method
* @callback getLastKeyCallback
* @param {Error} error An error instance representing the error during the execution.
* @param {Buffer} lastKey The Buffer value if the getLastKey method was successful.
*/
/**
* Get the last key of the range if no end key is provided to the RangeReader
* @method
* @param {object} tr Transaction.
* @param {object} reader RangeReader instance.
* @param {getLastKeyCallback} callback Callback.
* @return {undefined}
*/
RangeReader.prototype.getLastKey = function(tr, callback) {
if (this.end) {
debug(function(writer) {
return writer.buffer('end', this.end.key.toString('utf8'));
});
callback(null, this.end);
} else {
tr.getLastKey(this.begin, callback);
}
};
/**
* The callback format for the init method
* @callback initCallback
* @param {Error} error An error instance representing the error during the execution.
*/
/**
* Initialize the reader before iteration
* @abstract
* @param {object} tr Transaction.
* @param {object} reader RangeReader instance.
* @param {initCallback} callback Callback.
* @return {undefined}
*/
RangeReader.prototype.init = function(tr, callback) {
return callback(null);
};
/**
* The callback format for the getIterator method
* @callback getIteratorCallback
* @param {Error} error An error instance representing the error during the execution.
* @param {LazyIterator} iterator The LazyIterator instance if the getIterator method was successful.
*/
/**
* Get a LazyIterator instance for the current range read operation
* @method
* @param {object} tr Transaction.
* @param {object} reader RangeReader instance.
* @param {getIteratorCallback} callback Callback.
* @return {undefined}
*/
RangeReader.prototype.getIterator = function(tr, callback) {
var begin, iterator, options, ts;
debug(function(writer) {
return writer.log('getIterator');
});
options = {
limit: this.limit,
reverse: this.reverse,
streamingMode: this.streamingMode
};
ts = this.snapshot ? tr.snapshot : tr;
if (this.end || this.marker) {
begin = this.marker ? fdb.KeySelector.firstGreaterThan(this.marker) : this.begin;
this.getLastKey(tr, function(err, lastKey) {
var iterator;
if (err) {
callback(err);
} else {
iterator = ts.getRange(begin, lastKey, options);
debug(function(writer) {
writer.log('getLastKey');
writer.buffer('method', 'getRange');
writer.buffer('begin', resolveKey(begin).toString('utf8'));
writer.buffer('end', resolveKey(lastKey).toString('utf8'));
return writer.buffer('options', options);
});
callback(null, iterator);
}
});
} else {
iterator = ts.getRangeStartsWith(this.begin, options);
debug((function(_this) {
return function(writer) {
writer.buffer('method', 'getRangeStartsWith');
writer.buffer('prefix', resolveKey(_this.begin).toString('utf8'));
return writer.buffer('options', options);
};
})(this));
callback(null, iterator);
}
};
/**
* Iterate over array results
* @virtual
* @param {LazyIterator} iterator LazyIterator instance.
* @param {iterateCallback} callback Callback.
* @fires RangeReader#data
* @return {undefined}
*/
RangeReader.prototype.toArray = function(iterator, callback) {
iterator.toArray((function(_this) {
return function(err, arr) {
_this.emit('data', arr);
callback(err);
};
})(this));
};
/**
* Iterate over batch results
* @virtual
* @param {LazyIterator} iterator LazyIterator instance.
* @param {iterateCallback} callback Callback.
* @fires RangeReader#data
* @return {undefined}
*/
RangeReader.prototype.forEachBatch = function(iterator, callback) {
var func;
func = (function(_this) {
return function(arr, next) {
_this.emit('data', arr);
next();
};
})(this);
iterator.forEachBatch(func, callback);
};
/**
* Iterate over key-value pair results
* @virtual
* @param {LazyIterator} iterator LazyIterator instance.
* @param {iterateCallback} callback Callback.
* @fires RangeReader#data
* @return {undefined}
*/
RangeReader.prototype.forEach = function(iterator, callback) {
var func;
func = (function(_this) {
return function(kv, next) {
_this.emit('data', kv);
next();
};
})(this);
iterator.forEach(func, callback);
};
/**
* Execute the reader using an iterator type
* @virtual
* @param {object} [tr=null] transaction.
* @param {string} iteratorType batch|each|array.
* @fires RangeReader#error
* @fires RangeReader#continue
* @fires RangeReader#end
* @return {undefined}
*/
RangeReader.prototype.execute = function(tr, iteratorType) {
var complete, pastVersionCatchingCallback, toBeContinued, txi;
if (typeof tr === 'string') {
iteratorType = tr;
tr = db;
}
debug(function(writer) {
return writer.log('execute');
});
complete = (function(_this) {
return function(err, result) {
if (err) {
_this.emit('error', err);
} else {
_this.emit('end', result);
}
};
})(this);
toBeContinued = (function(_this) {
return function() {
debug(function(writer) {
return writer.log('continue');
});
tr.reset();
_this.emit('continue');
txi();
};
})(this);
pastVersionCatchingCallback = (function(_this) {
return function(err, result) {
if (err && _this.nonTransactional && err.message === 'past_version') {
toBeContinued();
} else {
complete(err, result);
}
};
})(this);
txi = (function(_this) {
return function() {
transactionalIterate(tr || db, _this, iteratorType, pastVersionCatchingCallback);
};
})(this);
txi();
};
return RangeReader;
})(EventEmitter);
};
}).call(this);