139 lines
3.7 KiB
JavaScript
139 lines
3.7 KiB
JavaScript
/*\
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title: $:/plugins/tiddlywiki/multiwikiserver/store/sql-engine.js
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type: application/javascript
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module-type: library
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Low level functions to work with the SQLite engine, either via better-sqlite3 or node-sqlite3-wasm.
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This class is intended to encapsulate all engine-specific logic.
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\*/
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(function() {
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/*
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Create a database engine. Options include:
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databasePath - path to the database file (can be ":memory:" or missing to get a temporary database)
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engine - wasm | better
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*/
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function SqlEngine(options) {
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options = options || {};
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// Initialise transaction mechanism
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this.transactionDepth = 0;
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// Initialise the statement cache
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this.statements = Object.create(null); // Hashmap by SQL text of statement objects
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// Choose engine
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this.engine = options.engine || "better"; // wasm | better
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// Create the database file directories if needed
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if(options.databasePath) {
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$tw.utils.createFileDirectories(options.databasePath);
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}
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// Create the database
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const databasePath = options.databasePath || ":memory:";
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let Database;
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switch(this.engine) {
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case "wasm":
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({ Database } = require("node-sqlite3-wasm"));
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break;
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case "better":
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Database = require("better-sqlite3");
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break;
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}
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this.db = new Database(databasePath,{
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verbose: undefined && console.log
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});
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// Turn on WAL mode for better-sqlite3
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if(this.engine === "better") {
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// See https://github.com/WiseLibs/better-sqlite3/blob/master/docs/performance.md
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this.db.pragma("journal_mode = WAL");
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}
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}
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SqlEngine.prototype.close = function() {
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for(const sql in this.statements) {
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if(this.statements[sql].finalize) {
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this.statements[sql].finalize();
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}
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}
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this.statements = Object.create(null);
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this.db.close();
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this.db = undefined;
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};
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SqlEngine.prototype.normaliseParams = function(params) {
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params = params || {};
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const result = Object.create(null);
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for(const paramName in params) {
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if(this.engine !== "wasm" && paramName.startsWith("$")) {
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result[paramName.slice(1)] = params[paramName];
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} else {
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result[paramName] = params[paramName];
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}
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}
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return result;
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};
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SqlEngine.prototype.prepareStatement = function(sql) {
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if(!(sql in this.statements)) {
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this.statements[sql] = this.db.prepare(sql);
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}
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return this.statements[sql];
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};
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SqlEngine.prototype.runStatement = function(sql,params) {
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params = this.normaliseParams(params);
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const statement = this.prepareStatement(sql);
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return statement.run(params);
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};
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SqlEngine.prototype.runStatementGet = function(sql,params) {
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params = this.normaliseParams(params);
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const statement = this.prepareStatement(sql);
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return statement.get(params);
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};
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SqlEngine.prototype.runStatementGetAll = function(sql,params) {
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params = this.normaliseParams(params);
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const statement = this.prepareStatement(sql);
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return statement.all(params);
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};
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SqlEngine.prototype.runStatements = function(sqlArray) {
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for(const sql of sqlArray) {
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this.runStatement(sql);
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}
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};
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/*
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Execute the given function in a transaction, committing if successful but rolling back if an error occurs. Returns whatever the given function returns.
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Calls to this function can be safely nested, but only the topmost call will actually take place in a transaction.
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TODO: better-sqlite3 provides its own transaction method which we should be using if available
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*/
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SqlEngine.prototype.transaction = function(fn) {
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const alreadyInTransaction = this.transactionDepth > 0;
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this.transactionDepth++;
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try {
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if(alreadyInTransaction) {
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return fn();
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} else {
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this.runStatement(`BEGIN TRANSACTION`);
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try {
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var result = fn();
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this.runStatement(`COMMIT TRANSACTION`);
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} catch(e) {
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this.runStatement(`ROLLBACK TRANSACTION`);
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throw(e);
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}
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return result;
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}
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} finally {
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this.transactionDepth--;
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}
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};
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exports.SqlEngine = SqlEngine;
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})(); |