1 files changed, 348 insertions, 0 deletions
diff --git a/mozglue/baseprofiler/core/ProfilerMarkers.cpp b/mozglue/baseprofiler/core/ProfilerMarkers.cpp
new file mode 100644
index 0000000000..eff6c7e364
--- /dev/null
+++ b/mozglue/baseprofiler/core/ProfilerMarkers.cpp
@@ -0,0 +1,348 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#include "mozilla/BaseProfilerMarkers.h"
+
+#include "mozilla/BaseProfilerUtils.h"
+
+#include <limits>
+
+namespace mozilla {
+namespace base_profiler_markers_detail {
+
+// We need an atomic type that can hold a `DeserializerTag`. (Atomic doesn't
+// work with too-small types.)
+using DeserializerTagAtomic = unsigned;
+
+// The atomic sDeserializerCount still also include bits that act as a "RWLock":
+// Whoever can set this bit gets exclusive access to the count and the whole
+// sMarkerTypeFunctions1Based array, guaranteeing that it cannot be modified.
+static constexpr DeserializerTagAtomic scExclusiveLock = 0x80'00'00'00u;
+// Code that wants shared access can add this value, then ensure there is no
+// exclusive lock, after which it's guaranteed that no exclusive lock can be
+// taken until the shared lock count goes back to zero.
+static constexpr DeserializerTagAtomic scSharedLockUnit = 0x00'01'00'00u;
+// This mask isolates the actual count value from the lock bits.
+static constexpr DeserializerTagAtomic scTagMask = 0x00'00'FF'FFu;
+
+// Number of currently-registered deserializers and other marker type functions.
+// The high bits contain lock bits, see above.
+static Atomic<DeserializerTagAtomic, MemoryOrdering::ReleaseAcquire>
+    sDeserializerCount{0};
+
+// This needs to be big enough to handle all possible marker types. If one day
+// this needs to be higher, the underlying DeserializerTag type will have to be
+// changed.
+static constexpr DeserializerTagAtomic DeserializerMax = 250;
+static_assert(DeserializerMax <= scTagMask,
+              "DeserializerMax doesn't fit in scTagMask");
+
+static_assert(
+    DeserializerMax <= std::numeric_limits<Streaming::DeserializerTag>::max(),
+    "The maximum number of deserializers must fit in the DeserializerTag type");
+
+// Array of marker type functions.
+// 1-based, i.e.: [0] -> tag 1, [DeserializerMax - 1] -> tag DeserializerMax.
+// Elements are added at the next available atomically-incremented
+// `sDeserializerCount` (minus 1) whenever a new marker type is used in a
+// Firefox session; the content is kept between profiler runs in that session.
+// There is theoretically a race between the increment and the time the entry is
+// fully written, but in practice all new elements are written (during
+// profiling, using a marker type for the first time) long before they are read
+// (after profiling is paused).
+static Streaming::MarkerTypeFunctions
+    sMarkerTypeFunctions1Based[DeserializerMax];
+
+/* static */ Streaming::DeserializerTag Streaming::TagForMarkerTypeFunctions(
+    Streaming::MarkerDataDeserializer aDeserializer,
+    Streaming::MarkerTypeNameFunction aMarkerTypeNameFunction,
+    Streaming::MarkerSchemaFunction aMarkerSchemaFunction) {
+  MOZ_RELEASE_ASSERT(!!aDeserializer);
+  MOZ_RELEASE_ASSERT(!!aMarkerTypeNameFunction);
+  MOZ_RELEASE_ASSERT(!!aMarkerSchemaFunction);
+
+  // Add a shared lock request, which will prevent future exclusive locking.
+  DeserializerTagAtomic tagWithLock = (sDeserializerCount += scSharedLockUnit);
+
+  // An exclusive locker may have arrived before us, just wait for it to finish.
+  while ((tagWithLock & scExclusiveLock) != 0u) {
+    tagWithLock = sDeserializerCount;
+  }
+
+  MOZ_ASSERT(
+      // This is equivalent to shifting right to only keep the lock counts.
+      tagWithLock / scSharedLockUnit <
+          // This is effectively half of the permissible shared lock range,
+          // that would mean way too many threads doing this work here!
+          scExclusiveLock / scSharedLockUnit / 2,
+      "The shared lock count is getting unexpectedly high, verify the "
+      "algorithm, and tweak constants if needed");
+
+  // Reserve a tag. Even if there are multiple shared-lock holders here, each
+  // one will get a different value, and therefore will access a different part
+  // of the sMarkerTypeFunctions1Based array.
+  const DeserializerTagAtomic tag = ++sDeserializerCount & scTagMask;
+
+  MOZ_RELEASE_ASSERT(
+      tag <= DeserializerMax,
+      "Too many deserializers, consider increasing DeserializerMax. "
+      "Or is a deserializer stored again and again?");
+  sMarkerTypeFunctions1Based[tag - 1] = {aDeserializer, aMarkerTypeNameFunction,
+                                         aMarkerSchemaFunction};
+
+  // And release our shared lock, to allow exclusive readers.
+  sDeserializerCount -= scSharedLockUnit;
+
+  return static_cast<DeserializerTag>(tag);
+}
+
+/* static */ Streaming::MarkerDataDeserializer Streaming::DeserializerForTag(
+    Streaming::DeserializerTag aTag) {
+  MOZ_RELEASE_ASSERT(
+      aTag > 0 && static_cast<DeserializerTagAtomic>(aTag) <=
+                      static_cast<DeserializerTagAtomic>(sDeserializerCount),
+      "Out-of-range tag value");
+  return sMarkerTypeFunctions1Based[aTag - 1].mMarkerDataDeserializer;
+}
+
+Streaming::LockedMarkerTypeFunctionsList::LockedMarkerTypeFunctionsList() {
+  for (;;) {
+    const DeserializerTagAtomic count = sDeserializerCount;
+    if ((count & scTagMask) != count) {
+      // Someone already has a lock, loop around.
+      continue;
+    }
+
+    // There are currently no locks, try to add our exclusive lock.
+    if (!sDeserializerCount.compareExchange(count, count | scExclusiveLock)) {
+      // Someone else modified sDeserializerCount since our read, loop around.
+      continue;
+    }
+
+    // We applied our exclusive lock, we can now read the list of functions,
+    // without interference until ~LockedMarkerTypeFunctionsList().
+    // (Note that sDeserializerCount may receive shared lock requests, but the
+    // count won't change.)
+    mMarkerTypeFunctionsSpan = {sMarkerTypeFunctions1Based, count};
+    break;
+  }
+}
+
+Streaming::LockedMarkerTypeFunctionsList::~LockedMarkerTypeFunctionsList() {
+  MOZ_ASSERT(
+      (sDeserializerCount & scExclusiveLock) == scExclusiveLock,
+      "sDeserializerCount should still have the the exclusive lock bit set");
+  MOZ_ASSERT(
+      (sDeserializerCount & scTagMask) ==
+          DeserializerTagAtomic(mMarkerTypeFunctionsSpan.size()),
+      "sDeserializerCount should have the same count since construction");
+  sDeserializerCount &= ~scExclusiveLock;
+}
+
+// Only accessed on the main thread.
+// Both profilers (Base and Gecko) could be active at the same time, so keep a
+// ref-count to only allocate at most one buffer at any time.
+static int sBufferForMainThreadAddMarkerRefCount = 0;
+static ProfileChunkedBuffer* sBufferForMainThreadAddMarker = nullptr;
+
+ProfileChunkedBuffer* GetClearedBufferForMainThreadAddMarker() {
+  if (!mozilla::baseprofiler::profiler_is_main_thread()) {
+    return nullptr;
+  }
+
+  if (sBufferForMainThreadAddMarker) {
+    MOZ_ASSERT(sBufferForMainThreadAddMarker->IsInSession(),
+               "sBufferForMainThreadAddMarker should always be in-session");
+    sBufferForMainThreadAddMarker->Clear();
+    MOZ_ASSERT(
+        sBufferForMainThreadAddMarker->IsInSession(),
+        "Cleared sBufferForMainThreadAddMarker should still be in-session");
+  }
+
+  return sBufferForMainThreadAddMarker;
+}
+
+MFBT_API void EnsureBufferForMainThreadAddMarker() {
+  if (!mozilla::baseprofiler::profiler_is_main_thread()) {
+    return;
+  }
+
+  if (sBufferForMainThreadAddMarkerRefCount++ == 0) {
+    // First `Ensure`, allocate the buffer.
+    MOZ_ASSERT(!sBufferForMainThreadAddMarker);
+    sBufferForMainThreadAddMarker = new ProfileChunkedBuffer(
+        ProfileChunkedBuffer::ThreadSafety::WithoutMutex,
+        MakeUnique<ProfileBufferChunkManagerSingle>(
+            ProfileBufferChunkManager::scExpectedMaximumStackSize));
+    MOZ_ASSERT(sBufferForMainThreadAddMarker);
+    MOZ_ASSERT(sBufferForMainThreadAddMarker->IsInSession());
+  }
+}
+
+MFBT_API void ReleaseBufferForMainThreadAddMarker() {
+  if (!mozilla::baseprofiler::profiler_is_main_thread()) {
+    return;
+  }
+
+  if (sBufferForMainThreadAddMarkerRefCount == 0) {
+    // Unexpected Release! This should not normally happen, but it's harmless in
+    // practice, it means the buffer is not alive anyway.
+    return;
+  }
+
+  MOZ_ASSERT(sBufferForMainThreadAddMarker);
+  MOZ_ASSERT(sBufferForMainThreadAddMarker->IsInSession());
+  if (--sBufferForMainThreadAddMarkerRefCount == 0) {
+    // Last `Release`, destroy the buffer.
+    delete sBufferForMainThreadAddMarker;
+    sBufferForMainThreadAddMarker = nullptr;
+  }
+}
+
+}  // namespace base_profiler_markers_detail
+
+void MarkerSchema::Stream(JSONWriter& aWriter,
+                          const Span<const char>& aName) && {
+  // The caller should have started a JSON array, in which we can add an object
+  // that defines a marker schema.
+
+  if (mLocations.empty()) {
+    // SpecialFrontendLocation case, don't output anything for this type.
+    return;
+  }
+
+  aWriter.StartObjectElement();
+  {
+    aWriter.StringProperty("name", aName);
+
+    if (!mChartLabel.empty()) {
+      aWriter.StringProperty("chartLabel", mChartLabel);
+    }
+
+    if (!mTooltipLabel.empty()) {
+      aWriter.StringProperty("tooltipLabel", mTooltipLabel);
+    }
+
+    if (!mTableLabel.empty()) {
+      aWriter.StringProperty("tableLabel", mTableLabel);
+    }
+
+    aWriter.StartArrayProperty("display");
+    {
+      for (Location location : mLocations) {
+        aWriter.StringElement(LocationToStringSpan(location));
+      }
+    }
+    aWriter.EndArray();
+
+    aWriter.StartArrayProperty("data");
+    {
+      for (const DataRow& row : mData) {
+        aWriter.StartObjectElement();
+        {
+          row.match(
+              [&aWriter](const DynamicData& aData) {
+                aWriter.StringProperty("key", aData.mKey);
+                if (aData.mLabel) {
+                  aWriter.StringProperty("label", *aData.mLabel);
+                }
+                aWriter.StringProperty("format",
+                                       FormatToStringSpan(aData.mFormat));
+                if (aData.mSearchable) {
+                  aWriter.BoolProperty(
+                      "searchable",
+                      *aData.mSearchable == Searchable::Searchable);
+                }
+              },
+              [&aWriter](const StaticData& aStaticData) {
+                aWriter.StringProperty("label", aStaticData.mLabel);
+                aWriter.StringProperty("value", aStaticData.mValue);
+              });
+        }
+        aWriter.EndObject();
+      }
+    }
+    aWriter.EndArray();
+  }
+  aWriter.EndObject();
+}
+
+/* static */
+Span<const char> MarkerSchema::LocationToStringSpan(
+    MarkerSchema::Location aLocation) {
+  switch (aLocation) {
+    case Location::MarkerChart:
+      return mozilla::MakeStringSpan("marker-chart");
+    case Location::MarkerTable:
+      return mozilla::MakeStringSpan("marker-table");
+    case Location::TimelineOverview:
+      return mozilla::MakeStringSpan("timeline-overview");
+    case Location::TimelineMemory:
+      return mozilla::MakeStringSpan("timeline-memory");
+    case Location::TimelineIPC:
+      return mozilla::MakeStringSpan("timeline-ipc");
+    case Location::TimelineFileIO:
+      return mozilla::MakeStringSpan("timeline-fileio");
+    case Location::StackChart:
+      return mozilla::MakeStringSpan("stack-chart");
+    default:
+      MOZ_CRASH("Unexpected Location enum");
+      return {};
+  }
+}
+
+/* static */
+Span<const char> MarkerSchema::FormatToStringSpan(
+    MarkerSchema::Format aFormat) {
+  switch (aFormat) {
+    case Format::Url:
+      return mozilla::MakeStringSpan("url");
+    case Format::FilePath:
+      return mozilla::MakeStringSpan("file-path");
+    case Format::String:
+      return mozilla::MakeStringSpan("string");
+    case Format::Duration:
+      return mozilla::MakeStringSpan("duration");
+    case Format::Time:
+      return mozilla::MakeStringSpan("time");
+    case Format::Seconds:
+      return mozilla::MakeStringSpan("seconds");
+    case Format::Milliseconds:
+      return mozilla::MakeStringSpan("milliseconds");
+    case Format::Microseconds:
+      return mozilla::MakeStringSpan("microseconds");
+    case Format::Nanoseconds:
+      return mozilla::MakeStringSpan("nanoseconds");
+    case Format::Bytes:
+      return mozilla::MakeStringSpan("bytes");
+    case Format::Percentage:
+      return mozilla::MakeStringSpan("percentage");
+    case Format::Integer:
+      return mozilla::MakeStringSpan("integer");
+    case Format::Decimal:
+      return mozilla::MakeStringSpan("decimal");
+    default:
+      MOZ_CRASH("Unexpected Format enum");
+      return {};
+  }
+}
+
+}  // namespace mozilla
+
+namespace mozilla::baseprofiler {
+template MFBT_API ProfileBufferBlockIndex AddMarker(const ProfilerString8View&,
+                                                    const MarkerCategory&,
+                                                    MarkerOptions&&,
+                                                    markers::TextMarker,
+                                                    const std::string&);
+
+template MFBT_API ProfileBufferBlockIndex
+AddMarkerToBuffer(ProfileChunkedBuffer&, const ProfilerString8View&,
+                  const MarkerCategory&, MarkerOptions&&, markers::NoPayload);
+
+template MFBT_API ProfileBufferBlockIndex AddMarkerToBuffer(
+    ProfileChunkedBuffer&, const ProfilerString8View&, const MarkerCategory&,
+    MarkerOptions&&, markers::TextMarker, const std::string&);
+}  // namespace mozilla::baseprofiler