Merge pull request #6 from trufflesuite/error-handling

Expand web3.js transport method wrapping to improve error reporting

error.js

@@ -0,0 +1,23 @@
+var inherits = require("util").inherits;
+var TruffleError = require("truffle-error");
+
+// HACK: string comparison seems to be only way to identify being unable to
+// connect to RPC node.
+var NOT_CONNECTED_MESSAGE = 'Invalid JSON RPC response: ""';
+
+function ProviderError(message, error) {
+  if (message == NOT_CONNECTED_MESSAGE) {
+    message = "Could not connect to your Ethereum client. " +
+      "Please check that your Ethereum client:\n" +
+      "    - is running\n" +
+      "    - is accepting RPC connections (i.e., \"--rpc\" option is used in geth)\n" +
+      "    - is accessible over the network\n" +
+      "    - is properly configured in your Truffle configuration file (truffle.js)\n";
+  }
+  ProviderError.super_.call(this, message);
+  this.message = message;
+}
+
+inherits(ProviderError, TruffleError);
+
+module.exports = ProviderError;

index.js

@@ -1,34 +1,10 @@
 var Web3 = require("web3");
 
+var wrapper = require('./wrapper');
+
 module.exports = {
   wrap: function(provider, options) {
-    options = options || {};
-
-    if (options.verbose || options.verboseRpc) {
-      this.makeVerbose(provider, options.logger);
-    }
-    return provider;
-  },
-
-  makeVerbose: function(provider, logger) {
-    logger = logger || console;
-
-    // // If you want to see what web3 is sending and receiving.
-    var oldAsync = provider.sendAsync;
-
-    if (oldAsync.is_verbose) return;
-
-    provider.sendAsync = function(options, callback) {
-      logger.log("   > " + JSON.stringify(options, null, 2).split("\n").join("\n   > "));
-      oldAsync.call(provider, options, function(error, result) {
-        if (error == null) {
-          logger.log(" <   " + JSON.stringify(result, null, 2).split("\n").join("\n <   "));
-        }
-        callback(error, result)
-      });
-    };
-
-    provider.sendAsync.is_verbose = true;
+    return wrapper.wrap(provider, options);
   },
 
   create: function(options) {

package.json

@@ -23,6 +23,7 @@
   },
   "homepage": "https://github.com/trufflesuite/truffle-provider#readme",
   "dependencies": {
+    "truffle-error": "0.0.2",
     "web3": "^0.18.0"
   },
   "devDependencies": {

wrapper.js

@@ -0,0 +1,138 @@
+var ProviderError = require('./error');
+
+module.exports = {
+  /*
+   * Web3.js Transport Wrapper
+   *
+   * Wraps an underlying web3 provider's RPC transport methods (send/sendAsync)
+   * for Truffle-specific purposes, mainly for logging / request verbosity.
+   */
+  wrap: function(provider, options) {
+    /* wrapping should be idempotent */
+    if (provider._alreadyWrapped) return provider;
+
+    /* setup options defaults */
+    options = options || {};
+    // custom logger
+    options.logger = options.logger || console;
+    // to see what web3 is sending and receiving.
+    options.verbose = options.verbose || options.verboseRpc || false;
+
+    /* create wrapper functions for before/after send */
+    var preHook = this.preHook(options);
+    var postHook = this.postHook(options);
+
+    var originalSend = provider.send.bind(provider);
+    var originalSendAsync = provider.sendAsync.bind(provider);
+
+    /* overwrite methods */
+    provider.send = this.send(originalSend, preHook, postHook);
+    provider.sendAsync = this.sendAsync(originalSendAsync, preHook, postHook);
+
+    /* mark as wrapped */
+    provider._alreadyWrapped = true;
+
+    return provider;
+  },
+
+  /*
+   * Transport Hook Generators
+   *
+   * Used to wrap underlying web3.js behavior before/after sending request
+   * payloads to the RPC.
+   *
+   * Transport hooks may be used to perform additional operations before/after
+   * sending, and/or to modify request/response data.
+   *
+   * Each generator accepts an `options` argument and uses it to construct
+   * and return a function.
+   *
+   * Returned functions accept relevant arguments and return potentially new
+   * versions of those arguments (for payload/result/error overrides)
+   */
+
+  // before send/sendAsync
+  preHook: function(options) {
+    return function(payload) {
+      if (options.verbose) {
+        // for request payload debugging
+        options.logger.log("   > " + JSON.stringify(payload, null, 2).split("\n").join("\n   > "));
+      }
+
+      return payload;
+    };
+  },
+
+  // after send/sendAsync
+  postHook: function(options) {
+    return function(payload, error, result) {
+      if (error != null) {
+        // wrap errors in internal error class
+        error = new ProviderError(error.message, error);
+        return [payload, error, result];
+      }
+
+      if (options.verbose) {
+        options.logger.log(" <   " + JSON.stringify(result, null, 2).split("\n").join("\n <   "));
+      }
+
+      return [payload, error, result];
+    };
+  },
+
+  /*
+   * Transport Method Generators
+   *
+   * Generate wrapped versions of `send`/`sendAsync`, given original method and
+   * transport hooks.
+   *
+   * Pre-condition: originals are bound correctly (`send.bind(provider)`)
+   *
+   * Return the wrapped function matching the original function's signature.
+   */
+
+  // wrap a `provider.send` function with behavior hooks
+  // returns a function(payload) to replace `provider.send`
+  send: function(originalSend, preHook, postHook) {
+    return function(payload) {
+      var result = null;
+      var error = null;
+
+      payload = preHook(payload);
+
+      try {
+        result = originalSend(payload);
+      } catch (e) {
+        error = e;
+      }
+
+      var modified = postHook(payload, error, result);
+      payload = modified[0];
+      error = modified[1];
+      result = modified[2];
+
+      if (error != null) {
+        throw error;
+      }
+
+      return result;
+    }
+  },
+
+  // wrap a `provider.sendAsync` function with behavior hooks
+  // returns a function(payload, callback) to replace `provider.sendAsync`
+  sendAsync: function(originalSendAsync, preHook, postHook) {
+    return function(payload, callback) {
+      payload = preHook(payload);
+
+      originalSendAsync(payload, function(error, result) {
+        var modified = postHook(payload, error, result);
+        payload = modified[0];
+        error = modified[1];
+        result = modified[2];
+
+        callback(error, result);
+      });
+    };
+  }
+}