Bug 1602739 - P1 - Add stats ID generator;r=mjf

Differential Revision: https://phabricator.services.mozilla.com/D57948

--HG--
extra : moz-landing-system : lando

media/webrtc/signaling/src/peerconnection/RTCStatsIdGenerator.cpp

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+
+#include "RTCStatsIdGenerator.h"
+#include "mozilla/RandomNum.h"
+#include <iostream>
+namespace mozilla {
+
+RTCStatsIdGenerator::RTCStatsIdGenerator()
+    : mSalt(RandomUint64().valueOr(0xa5a5a5a5)), mCounter(0) {}
+
+nsString RTCStatsIdGenerator::Id(const nsString& aKey) {
+  if (!aKey.Length()) {
+    MOZ_ASSERT(aKey.Length(), "Stats IDs should never be empty.");
+    return aKey;
+  }
+  if (mAllocated.find(aKey) == mAllocated.end()) {
+    mAllocated[aKey] = Generate();
+  }
+  return mAllocated[aKey];
+}
+
+nsString RTCStatsIdGenerator::Generate() {
+  auto random = RandomUint64().valueOr(0x1a22);
+  auto idNum = static_cast<uint32_t>(mSalt ^ ((mCounter++ << 16) | random));
+  nsString id;
+  id.AppendInt(idNum, 16);  // Append as hex
+  return id;
+}
+
+}  // namespace mozilla

media/webrtc/signaling/src/peerconnection/RTCStatsIdGenerator.h

@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+
+#ifndef _RTCSTATSIDGENERATOR_H_
+#define _RTCSTATSIDGENERATOR_H_
+
+#include "mozilla/Atomics.h"
+
+namespace mozilla {
+
+class RTCStatsIdGenerator {
+public:
+	RTCStatsIdGenerator();
+	nsString Id(const nsString& aKey);
+	NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RTCStatsIdGenerator);
+private:
+	virtual ~RTCStatsIdGenerator() {};
+	nsString Generate();
+
+	const uint64_t mSalt;
+	uint64_t mCounter;
+	std::map<nsString, nsString> mAllocated;
+};
+
+}
+#endif

media/webrtc/signaling/src/peerconnection/moz.build

@@ -30,6 +30,7 @@ UNIFIED_SOURCES += [
     'PeerConnectionCtx.cpp',
     'PeerConnectionImpl.cpp',
     'PeerConnectionMedia.cpp',
+    'RTCStatsIdGenerator.cpp',
     'RTCStatsReport.cpp',
     'TransceiverImpl.cpp',
     'WebrtcGlobalInformation.cpp',