Initial prototype of vmstats support, based on Dart VM Stats draft design doc.

runtime/bin/vmstats_impl.cc

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "bin/vmstats_impl.h"
+
+#include <sstream>
+
+#include "bin/fdutils.h"
+#include "bin/file.h"
+#include "bin/log.h"
+#include "bin/platform.h"
+#include "bin/socket.h"
+#include "bin/thread.h"
+#include "bin/utils.h"
+#include "include/dart_debugger_api.h"
+#include "platform/json.h"
+
+namespace dart {
+
+#define BUFSIZE 8192
+
+static const char* INDEX_HTML = "index.html";
+static const char* VMSTATS_HTML = "vmstats.html";
+static const char* DEFAULT_HOST = "localhost";
+
+// Global static pointer used to ensure a single instance of the class.
+VmStats* VmStats::instance_ = NULL;
+Monitor VmStats::instance_monitor_;
+Mutex VmStatusService::mutex_;
+
+
+void VmStats::Start(int port, const char* root_dir) {
+  if (instance_ != NULL) {
+    FATAL("VmStats already started.");
+  }
+  MonitorLocker ml(&instance_monitor_);
+  instance_ = new VmStats();
+  VmStatusService::InitOnce();
+  Socket::Initialize();
+
+  if (root_dir != NULL) {
+    instance_->root_directory_ = root_dir;
+  }
+
+  // TODO(tball): allow host to be specified.
+  char* host = const_cast<char*>(DEFAULT_HOST);
+  OSError* os_error;
+  const char* host_ip = Socket::LookupIPv4Address(host, &os_error);
+  if (host_ip == NULL) {
+    Log::PrintErr("Failed IP lookup of VmStats host %s: %s\n",
+                  host, os_error->message());
+    return;
+  }
+
+  const intptr_t BACKLOG = 128;  // Default value from HttpServer.dart
+  int64_t address = ServerSocket::CreateBindListen(host_ip, port, BACKLOG);
+  if (address < 0) {
+    Log::PrintErr("Failed binding VmStats socket: %s:%d\n", host, port);
+    return;
+  }
+  Log::Print("VmStats URL: http://%s:%d/\n", host,
+             Socket::GetPort(address));
+
+  instance_->running_ = true;
+  int errno = Thread::Start(WebServer, address);

[siva, 2013/02/25 06:47:41]

Where is the server socket represented by address closed?

[Tom Ball, 2013/02/26 21:50:49]

Saved bind_address to instance, closed in VmStats::Shutdown().

+  if (errno != 0) {
+    Log::PrintErr("Failed starting VmStats thread: %d\n", errno);
+    Shutdown();
+  }
+}
+
+
+void VmStats::Stop() {

[siva, 2013/02/25 06:47:41]

Need MonitorLocker ml&instance_monitor_); here as you
are modifying instance_->running_;

[Tom Ball, 2013/02/26 21:50:49]

Done.

+  if (instance_ != NULL) {
+    instance_->running_ = false;
+  }
+}
+
+
+void VmStats::Shutdown() {
+  MonitorLocker ml(&instance_monitor_);
+  delete instance_;
+  instance_ = NULL;
+}
+
+
+void VmStats::AddIsolate(IsolateData* isolate_data,
+                         Dart_Isolate isolate) {
+  MonitorLocker ml(&instance_monitor_);
+  if (instance_ != NULL) {
+    instance_->isolate_table_[isolate_data] = isolate;
+  }
+}
+
+
+void VmStats::RemoveIsolate(IsolateData* isolate_data) {
+  MonitorLocker ml(&instance_monitor_);
+  if (instance_ != NULL) {
+    instance_->isolate_table_.erase(isolate_data);
+  }
+}
+
+
+static const char* ContentType(const char* url) {
+  const char* suffix = strrchr(url, '.');
+  if (suffix != NULL) {
+    if (!strcmp(suffix, ".html")) {
+      return "text/html; charset=UTF-8";
+    }
+    if (!strcmp(suffix, ".dart")) {
+      return "application/dart; charset=UTF-8";
+    }
+    if (!strcmp(suffix, ".js")) {
+      return "application/javascript; charset=UTF-8";
+    }
+    if (!strcmp(suffix, ".css")) {
+      return "text/css; charset=UTF-8";
+    }
+    if (!strcmp(suffix, ".gif")) {
+      return "image/gif";
+    }
+    if (!strcmp(suffix, ".png")) {
+      return "image/png";
+    }
+    if (!strcmp(suffix, ".jpg") || !strcmp(suffix, ".jpeg")) {
+      return "image/jpeg";
+    }
+  }
+  return "text/plain";
+}
+
+
+void VmStats::WebServer(uword bind_address) {
+  while (instance_->running_) {
+    MonitorLocker ml(&instance_monitor_);

[siva, 2013/02/25 06:47:41]

This should be outside the while? otherwise you would be
accessing instance_running_ without a lock?

Actually holding the lock like this could be a bad idea as you have several
blocking calls in this code.

Not sure if this scheme of checking for instance_->running will bring this
thread down as you require that a connection needs to be made so that the accept
will wake up and then go back in the loop and check for instance_->running.

[Tom Ball, 2013/02/26 21:50:49]

On 2013/02/25 06:47:41, siva wrote:
As discussed, lock is just held when accessing instance_. instance_->running_
test above is now "while (true)", with test moved to right before VM calls.

+    intptr_t socket = ServerSocket::Accept(bind_address);
+    if (socket == ServerSocket::kTemporaryFailure) {
+      // Not a real failure, woke up but no connection available.
+      ml.Wait(100);
+      continue;
+    }
+    if (socket < 0) {
+      // Stop() closed the socket.
+      return;
+    }
+    FDUtils::SetBlocking(socket);
+
+    // TODO(tball): rewrite this to use STL, so as to eliminate the static
+    // buffer and support resource URLs that are longer than BUFSIZE.
+
+    // Read request.
+    // TODO(tball): support partial reads, possibly needed for POST uploads.
+    char buffer[BUFSIZE + 1];
+    int len = read(socket, buffer, BUFSIZE);
+    if (len <= 0) {
+      // Invalid HTTP request, ignore.
+      continue;
+    }
+    buffer[len] = '\0';
+
+    // Verify it's a GET request.
+    // TODO(tball): support POST requests.
+    if (strncmp("GET ", buffer, 4) != 0 && strncmp("get ", buffer, 4) != 0) {
+      Log::PrintErr("Unsupported HTTP request type");
+      const char* response = "HTTP/1.1 403 Forbidden\n"
+          "Content-Length: 120\n"
+          "Connection: close\n"
+          "Content-Type: text/html\n\n"
+          "<html><head>\n<title>403 Forbidden</title>\n</head>"
+          "<body>\n<h1>Forbidden</h1>\nUnsupported HTTP request type\n</body>"
+          "</html>\n";
+      Socket::Write(socket, response, strlen(response));
+      Socket::Close(socket);
+      continue;
+    }
+
+    // Extract GET URL, and null-terminate URL in case request line has
+    // HTTP version.
+    for (int i = 4; i < len; i++) {
+      if (buffer[i] == ' ') {
+        buffer[i] = '\0';
+      }
+    }
+    char* url = &buffer[4];
+
+    Log::Print("vmstats: %s requested\n", url);
+    char* content = NULL;
+
+    // Check for VmStats-specific URLs.
+    if (strcmp(url, "/isolates") == 0) {
+      content = instance_->IsolatesStatus();
+    } else {
+      // Check plug-ins.
+      content = VmStatusService::GetVmStatus(url);
+    }
+
+    if (content != NULL) {
+      size_t content_len = strlen(content);
+      len = snprintf(buffer, BUFSIZE,
+          "HTTP/1.1 200 OK\nContent-Type: application/json; charset=UTF-8\n"
+          "Content-Length: %d\n\n", content_len);
+      Socket::Write(socket, buffer, strlen(buffer));
+      Socket::Write(socket, content, content_len);
+      Socket::Write(socket, "\n", 1);
+      Socket::Write(socket, buffer, strlen(buffer));
+      free(content);
+    } else {
+      // No status content with this URL, return file or resource content.
+      std::string path(instance_->root_directory_);
+      path.append(url);
+
+      // Expand directory URLs.
+      if (strcmp(url, "/") == 0) {
+        path.append(VMSTATS_HTML);
+      } else if (url[strlen(url) - 1] == '/') {
+        path.append(INDEX_HTML);
+      }
+
+      bool success = false;
+      if (File::Exists(path.c_str())) {
+        File* f = File::Open(path.c_str(), File::kRead);
+        if (f != NULL) {
+          intptr_t len = f->Length();
+          char* text_buffer = reinterpret_cast<char*>(malloc(len));
+          if (f->ReadFully(text_buffer, len)) {
+            const char* content_type = ContentType(path.c_str());
+            snprintf(buffer, BUFSIZE,
+                "HTTP/1.1 200 OK\nContent-Type: %s\n"
+                "Content-Length: %d\n\n",
+                content_type, len);
+            Socket::Write(socket, buffer, strlen(buffer));
+            Socket::Write(socket, text_buffer, len);
+            Socket::Write(socket, "\n", 1);
+            success = true;
+          }
+          free(text_buffer);
+          delete f;
+        }
+      } else {
+        // TODO(tball): look up linked in resource.
+      }
+      if (!success) {
+        const char* response = "HTTP/1.1 404 Not Found\n\n";
+        Socket::Write(socket, response, strlen(response));
+      }
+    }
+    Socket::Close(socket);
+  }
+
+  Shutdown();
+}
+
+
+char* VmStats::IsolatesStatus() {
+  std::ostringstream stream;
+  stream << '{' << std::endl;
+  stream << "\"isolates\": [" << std::endl;
+  IsolateTable::iterator itr;
+  bool first = true;
+  for (itr = isolate_table_.begin(); itr != isolate_table_.end(); ++itr) {
+    Dart_Isolate isolate = itr->second;
+    static char request[512];
+    snprintf(request, sizeof(request), "/isolate/0x%llx",
+             reinterpret_cast<int64_t>(isolate));
+    char* status = VmStatusService::GetVmStatus(request);
+    if (status != NULL) {
+      stream << status;
+      if (!first) {
+        stream << "," << std::endl;
+      }
+      first = false;
+    }
+    free(status);
+  }
+  stream << std::endl << "]";
+  stream << std::endl << '}' << std::endl;
+  return strdup(stream.str().c_str());
+}
+
+
+// Global static pointer used to ensure a single instance of the class.
+VmStatusService* VmStatusService::instance_ = NULL;
+
+
+void VmStatusService::InitOnce() {
+  ASSERT(VmStatusService::instance_ == NULL);
+  VmStatusService::instance_ = new VmStatusService();
+
+  // Register built-in status plug-ins. RegisterPlugin is not used because
+  // this isn't called within an isolate, and because parameter checking
+  // isn't necessary.
+  instance_->RegisterPlugin(&Dart_GetVmStatus);
+
+  // TODO(tball): dynamically load any additional plug-ins.
+}
+
+
+int VmStatusService::RegisterPlugin(Dart_VmStatusCallback callback) {
+  MutexLocker ml(&mutex_);
+  if (callback == NULL) {
+    return -1;
+  }
+  VmStatusPlugin* plugin = new VmStatusPlugin(callback);
+  VmStatusPlugin* list = instance_->registered_plugin_list_;
+  if (list == NULL) {
+    instance_->registered_plugin_list_ = plugin;
+  } else {
+    list->Append(plugin);
+  }
+  return 0;
+}
+
+
+char* VmStatusService::GetVmStatus(const char* request) {
+  VmStatusPlugin* plugin = instance_->registered_plugin_list_;
+  while (plugin != NULL) {
+    char* result = (plugin->callback())(request);
+    if (result != NULL) {
+      return result;
+    }
+    plugin = plugin->next();
+  }
+  return NULL;
+}
+
+}  // namespace dart