|
| 1 | +'use strict' |
| 2 | +const Result = require('pg/lib/result.js') |
| 3 | +const prepare = require('pg/lib/utils.js').prepareValue |
| 4 | +const EventEmitter = require('events').EventEmitter |
| 5 | +const util = require('util') |
| 6 | + |
| 7 | +let nextUniqueID = 1 // concept borrowed from org.postgresql.core.v3.QueryExecutorImpl |
| 8 | + |
| 9 | +function Cursor (text, values, config) { |
| 10 | + EventEmitter.call(this) |
| 11 | + |
| 12 | + this._conf = config || {} |
| 13 | + this.text = text |
| 14 | + this.values = values ? values.map(prepare) : null |
| 15 | + this.connection = null |
| 16 | + this._queue = [] |
| 17 | + this.state = 'initialized' |
| 18 | + this._result = new Result(this._conf.rowMode, this._conf.types) |
| 19 | + this._cb = null |
| 20 | + this._rows = null |
| 21 | + this._portal = null |
| 22 | + this._ifNoData = this._ifNoData.bind(this) |
| 23 | + this._rowDescription = this._rowDescription.bind(this) |
| 24 | +} |
| 25 | + |
| 26 | +util.inherits(Cursor, EventEmitter) |
| 27 | + |
| 28 | +Cursor.prototype._ifNoData = function () { |
| 29 | + this.state = 'idle' |
| 30 | + this._shiftQueue() |
| 31 | +} |
| 32 | + |
| 33 | +Cursor.prototype._rowDescription = function () { |
| 34 | + if (this.connection) { |
| 35 | + this.connection.removeListener('noData', this._ifNoData) |
| 36 | + } |
| 37 | +} |
| 38 | + |
| 39 | +Cursor.prototype.submit = function (connection) { |
| 40 | + this.connection = connection |
| 41 | + this._portal = 'C_' + nextUniqueID++ |
| 42 | + |
| 43 | + const con = connection |
| 44 | + |
| 45 | + con.parse( |
| 46 | + { |
| 47 | + text: this.text |
| 48 | + }, |
| 49 | + true |
| 50 | + ) |
| 51 | + |
| 52 | + con.bind( |
| 53 | + { |
| 54 | + portal: this._portal, |
| 55 | + values: this.values |
| 56 | + }, |
| 57 | + true |
| 58 | + ) |
| 59 | + |
| 60 | + con.describe( |
| 61 | + { |
| 62 | + type: 'P', |
| 63 | + name: this._portal // AWS Redshift requires a portal name |
| 64 | + }, |
| 65 | + true |
| 66 | + ) |
| 67 | + |
| 68 | + con.flush() |
| 69 | + |
| 70 | + if (this._conf.types) { |
| 71 | + this._result._getTypeParser = this._conf.types.getTypeParser |
| 72 | + } |
| 73 | + |
| 74 | + con.once('noData', this._ifNoData) |
| 75 | + con.once('rowDescription', this._rowDescription) |
| 76 | +} |
| 77 | + |
| 78 | +Cursor.prototype._shiftQueue = function () { |
| 79 | + if (this._queue.length) { |
| 80 | + this._getRows.apply(this, this._queue.shift()) |
| 81 | + } |
| 82 | +} |
| 83 | + |
| 84 | +Cursor.prototype._closePortal = function () { |
| 85 | + // because we opened a named portal to stream results |
| 86 | + // we need to close the same named portal. Leaving a named portal |
| 87 | + // open can lock tables for modification if inside a transaction. |
| 88 | + // see https://github.com/brianc/node-pg-cursor/issues/56 |
| 89 | + this.connection.close({ type: 'P', name: this._portal }) |
| 90 | + this.connection.sync() |
| 91 | +} |
| 92 | + |
| 93 | +Cursor.prototype.handleRowDescription = function (msg) { |
| 94 | + this._result.addFields(msg.fields) |
| 95 | + this.state = 'idle' |
| 96 | + this._shiftQueue() |
| 97 | +} |
| 98 | + |
| 99 | +Cursor.prototype.handleDataRow = function (msg) { |
| 100 | + const row = this._result.parseRow(msg.fields) |
| 101 | + this.emit('row', row, this._result) |
| 102 | + this._rows.push(row) |
| 103 | +} |
| 104 | + |
| 105 | +Cursor.prototype._sendRows = function () { |
| 106 | + this.state = 'idle' |
| 107 | + setImmediate(() => { |
| 108 | + const cb = this._cb |
| 109 | + // remove callback before calling it |
| 110 | + // because likely a new one will be added |
| 111 | + // within the call to this callback |
| 112 | + this._cb = null |
| 113 | + if (cb) { |
| 114 | + this._result.rows = this._rows |
| 115 | + cb(null, this._rows, this._result) |
| 116 | + } |
| 117 | + this._rows = [] |
| 118 | + }) |
| 119 | +} |
| 120 | + |
| 121 | +Cursor.prototype.handleCommandComplete = function (msg) { |
| 122 | + this._result.addCommandComplete(msg) |
| 123 | + this._closePortal() |
| 124 | +} |
| 125 | + |
| 126 | +Cursor.prototype.handlePortalSuspended = function () { |
| 127 | + this._sendRows() |
| 128 | +} |
| 129 | + |
| 130 | +Cursor.prototype.handleReadyForQuery = function () { |
| 131 | + this._sendRows() |
| 132 | + this.state = 'done' |
| 133 | + this.emit('end', this._result) |
| 134 | +} |
| 135 | + |
| 136 | +Cursor.prototype.handleEmptyQuery = function () { |
| 137 | + this.connection.sync() |
| 138 | +} |
| 139 | + |
| 140 | +Cursor.prototype.handleError = function (msg) { |
| 141 | + this.connection.removeListener('noData', this._ifNoData) |
| 142 | + this.connection.removeListener('rowDescription', this._rowDescription) |
| 143 | + this.state = 'error' |
| 144 | + this._error = msg |
| 145 | + // satisfy any waiting callback |
| 146 | + if (this._cb) { |
| 147 | + this._cb(msg) |
| 148 | + } |
| 149 | + // dispatch error to all waiting callbacks |
| 150 | + for (let i = 0; i < this._queue.length; i++) { |
| 151 | + this._queue.pop()[1](msg) |
| 152 | + } |
| 153 | + |
| 154 | + if (this.listenerCount('error') > 0) { |
| 155 | + // only dispatch error events if we have a listener |
| 156 | + this.emit('error', msg) |
| 157 | + } |
| 158 | + // call sync to keep this connection from hanging |
| 159 | + this.connection.sync() |
| 160 | +} |
| 161 | + |
| 162 | +Cursor.prototype._getRows = function (rows, cb) { |
| 163 | + this.state = 'busy' |
| 164 | + this._cb = cb |
| 165 | + this._rows = [] |
| 166 | + const msg = { |
| 167 | + portal: this._portal, |
| 168 | + rows: rows |
| 169 | + } |
| 170 | + this.connection.execute(msg, true) |
| 171 | + this.connection.flush() |
| 172 | +} |
| 173 | + |
| 174 | +// users really shouldn't be calling 'end' here and terminating a connection to postgres |
| 175 | +// via the low level connection.end api |
| 176 | +Cursor.prototype.end = util.deprecate(function (cb) { |
| 177 | + if (this.state !== 'initialized') { |
| 178 | + this.connection.sync() |
| 179 | + } |
| 180 | + this.connection.once('end', cb) |
| 181 | + this.connection.end() |
| 182 | +}, 'Cursor.end is deprecated. Call end on the client itself to end a connection to the database.') |
| 183 | + |
| 184 | +Cursor.prototype.close = function (cb) { |
| 185 | + if (this.state === 'done') { |
| 186 | + if (cb) { |
| 187 | + return setImmediate(cb) |
| 188 | + } else { |
| 189 | + return |
| 190 | + } |
| 191 | + } |
| 192 | + this._closePortal() |
| 193 | + this.state = 'done' |
| 194 | + if (cb) { |
| 195 | + this.connection.once('closeComplete', function () { |
| 196 | + cb() |
| 197 | + }) |
| 198 | + } |
| 199 | +} |
| 200 | + |
| 201 | +Cursor.prototype.read = function (rows, cb) { |
| 202 | + if (this.state === 'idle') { |
| 203 | + return this._getRows(rows, cb) |
| 204 | + } |
| 205 | + if (this.state === 'busy' || this.state === 'initialized') { |
| 206 | + return this._queue.push([rows, cb]) |
| 207 | + } |
| 208 | + if (this.state === 'error') { |
| 209 | + return setImmediate(() => cb(this._error)) |
| 210 | + } |
| 211 | + if (this.state === 'done') { |
| 212 | + return setImmediate(() => cb(null, [])) |
| 213 | + } else { |
| 214 | + throw new Error('Unknown state: ' + this.state) |
| 215 | + } |
| 216 | +} |
| 217 | + |
| 218 | +module.exports = Cursor |
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