Support mysql tracing through the plugin API (#376)

PR-URL: #376

config.js

@@ -45,7 +45,8 @@ module.exports = {
       'koa': path.join(__dirname, 'src/plugins/plugin-koa.js'),
       'mongodb-core': path.join(__dirname, 'src/plugins/plugin-mongodb-core.js'),
       'redis': path.join(__dirname, 'src/plugins/plugin-redis.js'),
-      'restify': path.join(__dirname, 'src/plugins/plugin-restify.js')
+      'restify': path.join(__dirname, 'src/plugins/plugin-restify.js'),
+      'mysql': path.join(__dirname, 'src/plugins/plugin-mysql.js'),
     },
 
     // Valid entries are:

src/hooks/index.js

@@ -44,8 +44,6 @@ var toInstrument = Object.create(null, {
   'hapi': { enumerable: true, value: { file: './userspace/hook-hapi.js',
       patches: {} } },
   'http': { enumerable: true, value: { file: './core/hook-http.js',
-      patches: {} } },
-  'mysql': { enumerable: true, value: { file: './userspace/hook-mysql.js',
       patches: {} } }
 });
 

src/plugins/plugin-mysql.js

@@ -0,0 +1,95 @@
+/**
+ * Copyright 2017 Google Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+'use strict';
+
+var shimmer = require('shimmer');
+
+var SUPPORTED_VERSIONS = '^2.9.x';
+
+function createQueryWrap(api, createQuery) {
+  return function createQuery_trace(sql, values, cb) {
+    var span = api.createChildSpan({
+      name: 'mysql-query'
+    });
+    var query = createQuery.apply(this, arguments);
+    if (!span) {
+      return query;
+    }
+    if (api.enhancedDatabaseReportingEnabled()) {
+      span.addLabel('sql', query.sql);
+      if (query.values) {
+        span.addLabel('values', query.values);
+      }
+    }
+    api.wrapEmitter(query);
+    if (query._callback) {
+      query._callback = wrapCallback(api, span, query._callback);
+    } else {
+      query.on('end', function() {
+        span.endSpan();
+      });
+    }
+    return query;
+  };
+}
+
+function wrapCallback(api, span, done) {
+  var fn = function(err, res) {
+    if (api.enhancedDatabaseReportingEnabled()) {
+      if (err) {
+        span.addLabel('error', err);
+      }
+      if (res) {
+        span.addLabel('result', res);
+      }
+    }
+    span.endSpan();
+    if (done) {
+      done(err, res);
+    }
+  };
+  return api.wrap(fn);
+}
+
+function wrapGetConnection(api, getConnection) {
+  return function getConnection_trace(cb) {
+    return getConnection.call(this, api.wrap(cb));
+  };
+}
+
+module.exports = [
+  {
+    file: 'lib/Connection.js',
+    versions: SUPPORTED_VERSIONS,
+    patch: function(Connection, api) {
+      shimmer.wrap(Connection, 'createQuery', createQueryWrap.bind(null, api));
+    },
+    unpatch: function(Connection) {
+      shimmer.unwrap(Connection, 'createQuery');
+    }
+  },
+  {
+    file: 'lib/Pool.js',
+    versions: SUPPORTED_VERSIONS,
+    patch: function(Pool, api) {
+      shimmer.wrap(Pool.prototype, 'getConnection',
+                   wrapGetConnection.bind(null, api));
+    },
+    unpatch: function(Pool) {
+      shimmer.unwrap(Pool.prototype, 'getConnection');
+    }
+  }
+];