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qwen/nodejs/node_modules/pg/lib/query.js

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+'use strict'
+
+const { EventEmitter } = require('events')
+
+const Result = require('./result')
+const utils = require('./utils')
+
+class Query extends EventEmitter {
+  constructor(config, values, callback) {
+    super()
+
+    config = utils.normalizeQueryConfig(config, values, callback)
+
+    this.text = config.text
+    this.values = config.values
+    this.rows = config.rows
+    this.types = config.types
+    this.name = config.name
+    this.queryMode = config.queryMode
+    this.binary = config.binary
+    // use unique portal name each time
+    this.portal = config.portal || ''
+    this.callback = config.callback
+    this._rowMode = config.rowMode
+    if (process.domain && config.callback) {
+      this.callback = process.domain.bind(config.callback)
+    }
+    this._result = new Result(this._rowMode, this.types)
+
+    // potential for multiple results
+    this._results = this._result
+    this._canceledDueToError = false
+  }
+
+  requiresPreparation() {
+    if (this.queryMode === 'extended') {
+      return true
+    }
+
+    // named queries must always be prepared
+    if (this.name) {
+      return true
+    }
+    // always prepare if there are max number of rows expected per
+    // portal execution
+    if (this.rows) {
+      return true
+    }
+    // don't prepare empty text queries
+    if (!this.text) {
+      return false
+    }
+    // prepare if there are values
+    if (!this.values) {
+      return false
+    }
+    return this.values.length > 0
+  }
+
+  _checkForMultirow() {
+    // if we already have a result with a command property
+    // then we've already executed one query in a multi-statement simple query
+    // turn our results into an array of results
+    if (this._result.command) {
+      if (!Array.isArray(this._results)) {
+        this._results = [this._result]
+      }
+      this._result = new Result(this._rowMode, this._result._types)
+      this._results.push(this._result)
+    }
+  }
+
+  // associates row metadata from the supplied
+  // message with this query object
+  // metadata used when parsing row results
+  handleRowDescription(msg) {
+    this._checkForMultirow()
+    this._result.addFields(msg.fields)
+    this._accumulateRows = this.callback || !this.listeners('row').length
+  }
+
+  handleDataRow(msg) {
+    let row
+
+    if (this._canceledDueToError) {
+      return
+    }
+
+    try {
+      row = this._result.parseRow(msg.fields)
+    } catch (err) {
+      this._canceledDueToError = err
+      return
+    }
+
+    this.emit('row', row, this._result)
+    if (this._accumulateRows) {
+      this._result.addRow(row)
+    }
+  }
+
+  handleCommandComplete(msg, connection) {
+    this._checkForMultirow()
+    this._result.addCommandComplete(msg)
+    // need to sync after each command complete of a prepared statement
+    // if we were using a row count which results in multiple calls to _getRows
+    if (this.rows) {
+      connection.sync()
+    }
+  }
+
+  // if a named prepared statement is created with empty query text
+  // the backend will send an emptyQuery message but *not* a command complete message
+  // since we pipeline sync immediately after execute we don't need to do anything here
+  // unless we have rows specified, in which case we did not pipeline the initial sync call
+  handleEmptyQuery(connection) {
+    if (this.rows) {
+      connection.sync()
+    }
+  }
+
+  handleError(err, connection) {
+    // need to sync after error during a prepared statement
+    if (this._canceledDueToError) {
+      err = this._canceledDueToError
+      this._canceledDueToError = false
+    }
+    // if callback supplied do not emit error event as uncaught error
+    // events will bubble up to node process
+    if (this.callback) {
+      return this.callback(err)
+    }
+    this.emit('error', err)
+  }
+
+  handleReadyForQuery(con) {
+    if (this._canceledDueToError) {
+      return this.handleError(this._canceledDueToError, con)
+    }
+    if (this.callback) {
+      try {
+        this.callback(null, this._results)
+      } catch (err) {
+        process.nextTick(() => {
+          throw err
+        })
+      }
+    }
+    this.emit('end', this._results)
+  }
+
+  submit(connection) {
+    if (typeof this.text !== 'string' && typeof this.name !== 'string') {
+      return new Error('A query must have either text or a name. Supplying neither is unsupported.')
+    }
+    const previous = connection.parsedStatements[this.name]
+    if (this.text && previous && this.text !== previous) {
+      return new Error(`Prepared statements must be unique - '${this.name}' was used for a different statement`)
+    }
+    if (this.values && !Array.isArray(this.values)) {
+      return new Error('Query values must be an array')
+    }
+    if (this.requiresPreparation()) {
+      // If we're using the extended query protocol we fire off several separate commands
+      // to the backend. On some versions of node & some operating system versions
+      // the network stack writes each message separately instead of buffering them together
+      // causing the client & network to send more slowly. Corking & uncorking the stream
+      // allows node to buffer up the messages internally before sending them all off at once.
+      // note: we're checking for existence of cork/uncork because some versions of streams
+      // might not have this (cloudflare?)
+      connection.stream.cork && connection.stream.cork()
+      try {
+        this.prepare(connection)
+      } finally {
+        // while unlikely for this.prepare to throw, if it does & we don't uncork this stream
+        // this client becomes unresponsive, so put in finally block "just in case"
+        connection.stream.uncork && connection.stream.uncork()
+      }
+    } else {
+      connection.query(this.text)
+    }
+    return null
+  }
+
+  hasBeenParsed(connection) {
+    return this.name && connection.parsedStatements[this.name]
+  }
+
+  handlePortalSuspended(connection) {
+    this._getRows(connection, this.rows)
+  }
+
+  _getRows(connection, rows) {
+    connection.execute({
+      portal: this.portal,
+      rows: rows,
+    })
+    // if we're not reading pages of rows send the sync command
+    // to indicate the pipeline is finished
+    if (!rows) {
+      connection.sync()
+    } else {
+      // otherwise flush the call out to read more rows
+      connection.flush()
+    }
+  }
+
+  // http://developer.postgresql.org/pgdocs/postgres/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY
+  prepare(connection) {
+    // TODO refactor this poor encapsulation
+    if (!this.hasBeenParsed(connection)) {
+      connection.parse({
+        text: this.text,
+        name: this.name,
+        types: this.types,
+      })
+    }
+
+    // because we're mapping user supplied values to
+    // postgres wire protocol compatible values it could
+    // throw an exception, so try/catch this section
+    try {
+      connection.bind({
+        portal: this.portal,
+        statement: this.name,
+        values: this.values,
+        binary: this.binary,
+        valueMapper: utils.prepareValue,
+      })
+    } catch (err) {
+      this.handleError(err, connection)
+      return
+    }
+
+    connection.describe({
+      type: 'P',
+      name: this.portal || '',
+    })
+
+    this._getRows(connection, this.rows)
+  }
+
+  handleCopyInResponse(connection) {
+    connection.sendCopyFail('No source stream defined')
+  }
+
+  handleCopyData(msg, connection) {
+    // noop
+  }
+}
+
+module.exports = Query