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node_modules/mongodb-core/lib/transactions.js

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+'use strict';
+const MongoError = require('./error').MongoError;
+
+let TxnState;
+let stateMachine;
+
+(() => {
+  const NO_TRANSACTION = 'NO_TRANSACTION';
+  const STARTING_TRANSACTION = 'STARTING_TRANSACTION';
+  const TRANSACTION_IN_PROGRESS = 'TRANSACTION_IN_PROGRESS';
+  const TRANSACTION_COMMITTED = 'TRANSACTION_COMMITTED';
+  const TRANSACTION_COMMITTED_EMPTY = 'TRANSACTION_COMMITTED_EMPTY';
+  const TRANSACTION_ABORTED = 'TRANSACTION_ABORTED';
+
+  TxnState = {
+    NO_TRANSACTION,
+    STARTING_TRANSACTION,
+    TRANSACTION_IN_PROGRESS,
+    TRANSACTION_COMMITTED,
+    TRANSACTION_COMMITTED_EMPTY,
+    TRANSACTION_ABORTED
+  };
+
+  stateMachine = {
+    [NO_TRANSACTION]: [NO_TRANSACTION, STARTING_TRANSACTION],
+    [STARTING_TRANSACTION]: [
+      TRANSACTION_IN_PROGRESS,
+      TRANSACTION_COMMITTED,
+      TRANSACTION_COMMITTED_EMPTY,
+      TRANSACTION_ABORTED
+    ],
+    [TRANSACTION_IN_PROGRESS]: [
+      TRANSACTION_IN_PROGRESS,
+      TRANSACTION_COMMITTED,
+      TRANSACTION_ABORTED
+    ],
+    [TRANSACTION_COMMITTED]: [
+      TRANSACTION_COMMITTED,
+      TRANSACTION_COMMITTED_EMPTY,
+      STARTING_TRANSACTION,
+      NO_TRANSACTION
+    ],
+    [TRANSACTION_ABORTED]: [STARTING_TRANSACTION, NO_TRANSACTION],
+    [TRANSACTION_COMMITTED_EMPTY]: [TRANSACTION_COMMITTED_EMPTY, NO_TRANSACTION]
+  };
+})();
+
+/**
+ * The MongoDB ReadConcern, which allows for control of the consistency and isolation properties
+ * of the data read from replica sets and replica set shards.
+ * @typedef {Object} ReadConcern
+ * @property {'local'|'available'|'majority'|'linearizable'|'snapshot'} level The readConcern Level
+ * @see https://docs.mongodb.com/manual/reference/read-concern/
+ */
+
+/**
+ * A MongoDB WriteConcern, which describes the level of acknowledgement
+ * requested from MongoDB for write operations.
+ * @typedef {Object} WriteConcern
+ * @property {number|'majority'|string} [w=1] requests acknowledgement that the write operation has
+ * propagated to a specified number of mongod hosts
+ * @property {boolean} [j=false] requests acknowledgement from MongoDB that the write operation has
+ * been written to the journal
+ * @property {number} [wtimeout] a time limit, in milliseconds, for the write concern
+ * @see https://docs.mongodb.com/manual/reference/write-concern/
+ */
+
+/**
+ * Configuration options for a transaction.
+ * @typedef {Object} TransactionOptions
+ * @property {ReadConcern} [readConcern] A default read concern for commands in this transaction
+ * @property {WriteConcern} [writeConcern] A default writeConcern for commands in this transaction
+ * @property {ReadPreference} [readPreference] A default read preference for commands in this transaction
+ */
+
+/**
+ * A class maintaining state related to a server transaction. Internal Only
+ * @ignore
+ */
+class Transaction {
+  /**
+   * Create a transaction
+   *
+   * @ignore
+   * @param {TransactionOptions} [options] Optional settings
+   */
+  constructor(options) {
+    options = options || {};
+
+    this.state = TxnState.NO_TRANSACTION;
+    this.options = {};
+
+    if (options.writeConcern || typeof options.w !== 'undefined') {
+      const w = options.writeConcern ? options.writeConcern.w : options.w;
+      if (w <= 0) {
+        throw new MongoError('Transactions do not support unacknowledged write concern');
+      }
+
+      this.options.writeConcern = options.writeConcern ? options.writeConcern : { w: options.w };
+    }
+
+    if (options.readConcern) this.options.readConcern = options.readConcern;
+    if (options.readPreference) this.options.readPreference = options.readPreference;
+  }
+
+  /**
+   * @ignore
+   * @return Whether this session is presently in a transaction
+   */
+  get isActive() {
+    return (
+      [TxnState.STARTING_TRANSACTION, TxnState.TRANSACTION_IN_PROGRESS].indexOf(this.state) !== -1
+    );
+  }
+
+  /**
+   * Transition the transaction in the state machine
+   * @ignore
+   * @param {TxnState} state The new state to transition to
+   */
+  transition(nextState) {
+    const nextStates = stateMachine[this.state];
+    if (nextStates && nextStates.indexOf(nextState) !== -1) {
+      this.state = nextState;
+      return;
+    }
+
+    throw new MongoError(
+      `Attempted illegal state transition from [${this.state}] to [${nextState}]`
+    );
+  }
+}
+
+module.exports = { TxnState, Transaction };