sharing WIP

src/share/sql.js

@@ -0,0 +1,167 @@
+"use strict";
+
+const log = require('../services/log');
+const Database = require('better-sqlite3');
+const dataDir = require('../services/data_dir');
+
+const dbConnection = new Database(dataDir.DOCUMENT_PATH, { readonly: true });
+
+[`exit`, `SIGINT`, `SIGUSR1`, `SIGUSR2`, `SIGTERM`].forEach(eventType => {
+    process.on(eventType, () => {
+        if (dbConnection) {
+            // closing connection is especially important to fold -wal file into the main DB file
+            // (see https://sqlite.org/tempfiles.html for details)
+            dbConnection.close();
+        }
+    });
+});
+
+const statementCache = {};
+
+function stmt(sql) {
+    if (!(sql in statementCache)) {
+        statementCache[sql] = dbConnection.prepare(sql);
+    }
+
+    return statementCache[sql];
+}
+
+function getRow(query, params = []) {
+    return wrap(query, s => s.get(params));
+}
+
+function getRowOrNull(query, params = []) {
+    const all = getRows(query, params);
+
+    return all.length > 0 ? all[0] : null;
+}
+
+function getValue(query, params = []) {
+    const row = getRowOrNull(query, params);
+
+    if (!row) {
+        return null;
+    }
+
+    return row[Object.keys(row)[0]];
+}
+
+// smaller values can result in better performance due to better usage of statement cache
+const PARAM_LIMIT = 100;
+
+function getManyRows(query, params) {
+    let results = [];
+
+    while (params.length > 0) {
+        const curParams = params.slice(0, Math.min(params.length, PARAM_LIMIT));
+        params = params.slice(curParams.length);
+
+        const curParamsObj = {};
+
+        let j = 1;
+        for (const param of curParams) {
+            curParamsObj['param' + j++] = param;
+        }
+
+        let i = 1;
+        const questionMarks = curParams.map(() => ":param" + i++).join(",");
+        const curQuery = query.replace(/\?\?\?/g, questionMarks);
+
+        const statement = curParams.length === PARAM_LIMIT
+            ? stmt(curQuery)
+            : dbConnection.prepare(curQuery);
+
+        const subResults = statement.all(curParamsObj);
+        results = results.concat(subResults);
+    }
+
+    return results;
+}
+
+function getRows(query, params = []) {
+    return wrap(query, s => s.all(params));
+}
+
+function getRawRows(query, params = []) {
+    return wrap(query, s => s.raw().all(params));
+}
+
+function iterateRows(query, params = []) {
+    return stmt(query).iterate(params);
+}
+
+function getMap(query, params = []) {
+    const map = {};
+    const results = getRows(query, params);
+
+    for (const row of results) {
+        const keys = Object.keys(row);
+
+        map[row[keys[0]]] = row[keys[1]];
+    }
+
+    return map;
+}
+
+function getColumn(query, params = []) {
+    const list = [];
+    const result = getRows(query, params);
+
+    if (result.length === 0) {
+        return list;
+    }
+
+    const key = Object.keys(result[0])[0];
+
+    for (const row of result) {
+        list.push(row[key]);
+    }
+
+    return list;
+}
+
+function wrap(query, func) {
+    const startTimestamp = Date.now();
+    let result;
+
+    try {
+        result = func(stmt(query));
+    }
+    catch (e) {
+        if (e.message.includes("The database connection is not open")) {
+            // this often happens on killing the app which puts these alerts in front of user
+            // in these cases error should be simply ignored.
+            console.log(e.message);
+
+            return null
+        }
+
+        throw e;
+    }
+
+    const milliseconds = Date.now() - startTimestamp;
+
+    if (milliseconds >= 20) {
+        if (query.includes("WITH RECURSIVE")) {
+            log.info(`Slow recursive query took ${milliseconds}ms.`);
+        }
+        else {
+            log.info(`Slow query took ${milliseconds}ms: ${query.trim().replace(/\s+/g, " ")}`);
+        }
+    }
+
+    return result;
+}
+
+module.exports = {
+    dbConnection,
+    getValue,
+    getRow,
+    getRowOrNull,
+    getRows,
+    getRawRows,
+    iterateRows,
+    getManyRows,
+    getMap,
+    getColumn
+};