Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1487 insertions, 0 deletions

diff --git a/tools/profiler/gecko/nsProfiler.cpp b/tools/profiler/gecko/nsProfiler.cpp
new file mode 100644
index 0000000000..66e32ce2bc
--- /dev/null
+++ b/tools/profiler/gecko/nsProfiler.cpp
@@ -0,0 +1,1487 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "nsProfiler.h"
+
+#include <fstream>
+#include <limits>
+#include <sstream>
+#include <string>
+#include <utility>
+
+#include "GeckoProfiler.h"
+#include "ProfilerControl.h"
+#include "ProfilerParent.h"
+#include "js/Array.h"  // JS::NewArrayObject
+#include "js/JSON.h"
+#include "js/PropertyAndElement.h"  // JS_SetElement
+#include "js/Value.h"
+#include "json/json.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/JSONStringWriteFuncs.h"
+#include "mozilla/SchedulerGroup.h"
+#include "mozilla/Services.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/Preferences.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsILoadContext.h"
+#include "nsIWebNavigation.h"
+#include "nsProfilerStartParams.h"
+#include "nsProxyRelease.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "platform.h"
+#include "shared-libraries.h"
+#include "zlib.h"
+
+#ifndef ANDROID
+#  include <cstdio>
+#else
+#  include <android/log.h>
+#endif
+
+using namespace mozilla;
+
+using dom::AutoJSAPI;
+using dom::Promise;
+using std::string;
+
+static constexpr size_t scLengthMax = size_t(JS::MaxStringLength);
+// Used when trying to add more JSON data, to account for the extra space needed
+// for the log and to close the profile.
+static constexpr size_t scLengthAccumulationThreshold = scLengthMax - 16 * 1024;
+
+NS_IMPL_ISUPPORTS(nsProfiler, nsIProfiler)
+
+nsProfiler::nsProfiler() : mGathering(false) {}
+
+nsProfiler::~nsProfiler() {
+  if (mSymbolTableThread) {
+    mSymbolTableThread->Shutdown();
+  }
+  ResetGathering(NS_ERROR_ILLEGAL_DURING_SHUTDOWN);
+}
+
+nsresult nsProfiler::Init() { return NS_OK; }
+
+template <typename JsonLogObjectUpdater>
+void nsProfiler::Log(JsonLogObjectUpdater&& aJsonLogObjectUpdater) {
+  if (mGatheringLog) {
+    MOZ_ASSERT(mGatheringLog->isObject());
+    std::forward<JsonLogObjectUpdater>(aJsonLogObjectUpdater)(*mGatheringLog);
+    MOZ_ASSERT(mGatheringLog->isObject());
+  }
+}
+
+template <typename JsonArrayAppender>
+void nsProfiler::LogEvent(JsonArrayAppender&& aJsonArrayAppender) {
+  Log([&](Json::Value& aRoot) {
+    Json::Value& events = aRoot[Json::StaticString{"events"}];
+    if (!events.isArray()) {
+      events = Json::Value{Json::arrayValue};
+    }
+    Json::Value newEvent{Json::arrayValue};
+    newEvent.append(ProfilingLog::Timestamp());
+    std::forward<JsonArrayAppender>(aJsonArrayAppender)(newEvent);
+    MOZ_ASSERT(newEvent.isArray());
+    events.append(std::move(newEvent));
+  });
+}
+
+void nsProfiler::LogEventLiteralString(const char* aEventString) {
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{aEventString});
+  });
+}
+
+static nsresult FillVectorFromStringArray(Vector<const char*>& aVector,
+                                          const nsTArray<nsCString>& aArray) {
+  if (NS_WARN_IF(!aVector.reserve(aArray.Length()))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  for (auto& entry : aArray) {
+    aVector.infallibleAppend(entry.get());
+  }
+  return NS_OK;
+}
+
+// Given a PromiseReturningFunction: () -> GenericPromise,
+// run the function, and return a JS Promise (through aPromise) that will be
+// resolved when the function's GenericPromise gets resolved.
+template <typename PromiseReturningFunction>
+static nsresult RunFunctionAndConvertPromise(
+    JSContext* aCx, Promise** aPromise,
+    PromiseReturningFunction&& aPromiseReturningFunction) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  std::forward<PromiseReturningFunction>(aPromiseReturningFunction)()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [promise](GenericPromise::ResolveOrRejectValue&&) {
+        promise->MaybeResolveWithUndefined();
+      });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::StartProfiler(uint32_t aEntries, double aInterval,
+                          const nsTArray<nsCString>& aFeatures,
+                          const nsTArray<nsCString>& aFilters,
+                          uint64_t aActiveTabID, double aDuration,
+                          JSContext* aCx, Promise** aPromise) {
+  ResetGathering(NS_ERROR_DOM_ABORT_ERR);
+
+  Vector<const char*> featureStringVector;
+  nsresult rv = FillVectorFromStringArray(featureStringVector, aFeatures);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  uint32_t features = ParseFeaturesFromStringArray(
+      featureStringVector.begin(), featureStringVector.length());
+  Maybe<double> duration = aDuration > 0.0 ? Some(aDuration) : Nothing();
+
+  Vector<const char*> filterStringVector;
+  rv = FillVectorFromStringArray(filterStringVector, aFilters);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return RunFunctionAndConvertPromise(aCx, aPromise, [&]() {
+    return profiler_start(PowerOfTwo32(aEntries), aInterval, features,
+                          filterStringVector.begin(),
+                          filterStringVector.length(), aActiveTabID, duration);
+  });
+}
+
+NS_IMETHODIMP
+nsProfiler::StopProfiler(JSContext* aCx, Promise** aPromise) {
+  ResetGathering(NS_ERROR_DOM_ABORT_ERR);
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_stop(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::IsPaused(bool* aIsPaused) {
+  *aIsPaused = profiler_is_paused();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::Pause(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_pause(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::Resume(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_resume(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::IsSamplingPaused(bool* aIsSamplingPaused) {
+  *aIsSamplingPaused = profiler_is_sampling_paused();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::PauseSampling(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(
+      aCx, aPromise, []() { return profiler_pause_sampling(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::ResumeSampling(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(
+      aCx, aPromise, []() { return profiler_resume_sampling(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::ClearAllPages() {
+  profiler_clear_all_pages();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::WaitOnePeriodicSampling(JSContext* aCx, Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  // The callback cannot officially own the promise RefPtr directly, because
+  // `Promise` doesn't support multi-threading, and the callback could destroy
+  // the promise in the sampler thread.
+  // `nsMainThreadPtrHandle` ensures that the promise can only be destroyed on
+  // the main thread. And the invocation from the Sampler thread immediately
+  // dispatches a task back to the main thread, to resolve/reject the promise.
+  // The lambda needs to be `mutable`, to allow moving-from
+  // `promiseHandleInSampler`.
+  if (!profiler_callback_after_sampling(
+          [promiseHandleInSampler = nsMainThreadPtrHandle<Promise>(
+               new nsMainThreadPtrHolder<Promise>(
+                   "WaitOnePeriodicSampling promise for Sampler", promise))](
+              SamplingState aSamplingState) mutable {
+            SchedulerGroup::Dispatch(
+                TaskCategory::Other,
+                NS_NewRunnableFunction(
+                    "nsProfiler::WaitOnePeriodicSampling result on main thread",
+                    [promiseHandleInMT = std::move(promiseHandleInSampler),
+                     aSamplingState]() mutable {
+                      switch (aSamplingState) {
+                        case SamplingState::JustStopped:
+                        case SamplingState::SamplingPaused:
+                          promiseHandleInMT->MaybeReject(NS_ERROR_FAILURE);
+                          break;
+
+                        case SamplingState::NoStackSamplingCompleted:
+                        case SamplingState::SamplingCompleted:
+                          // The parent process has succesfully done a sampling,
+                          // check the child processes (if any).
+                          ProfilerParent::WaitOnePeriodicSampling()->Then(
+                              GetMainThreadSerialEventTarget(), __func__,
+                              [promiseHandleInMT =
+                                   std::move(promiseHandleInMT)](
+                                  GenericPromise::ResolveOrRejectValue&&) {
+                                promiseHandleInMT->MaybeResolveWithUndefined();
+                              });
+                          break;
+
+                        default:
+                          MOZ_ASSERT(false, "Unexpected SamplingState value");
+                          promiseHandleInMT->MaybeReject(
+                              NS_ERROR_DOM_UNKNOWN_ERR);
+                          break;
+                      }
+                    }));
+          })) {
+    // Callback was not added (e.g., profiler is not running) and will never be
+    // invoked, so we need to resolve the promise here.
+    promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+  }
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfile(double aSinceTime, char** aProfile) {
+  mozilla::UniquePtr<char[]> profile = profiler_get_profile(aSinceTime);
+  *aProfile = profile.release();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetSharedLibraries(JSContext* aCx,
+                               JS::MutableHandle<JS::Value> aResult) {
+  JS::Rooted<JS::Value> val(aCx);
+  {
+    JSONStringWriteFunc<nsCString> buffer;
+    JSONWriter w(buffer, JSONWriter::SingleLineStyle);
+    w.StartArrayElement();
+    SharedLibraryInfo sharedLibraryInfo = SharedLibraryInfo::GetInfoForSelf();
+    sharedLibraryInfo.SortByAddress();
+    AppendSharedLibraries(w, sharedLibraryInfo);
+    w.EndArray();
+    NS_ConvertUTF8toUTF16 buffer16(buffer.StringCRef());
+    MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx,
+                                 static_cast<const char16_t*>(buffer16.get()),
+                                 buffer16.Length(), &val));
+  }
+  JS::Rooted<JSObject*> obj(aCx, &val.toObject());
+  if (!obj) {
+    return NS_ERROR_FAILURE;
+  }
+  aResult.setObject(*obj);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetActiveConfiguration(JSContext* aCx,
+                                   JS::MutableHandle<JS::Value> aResult) {
+  JS::Rooted<JS::Value> jsValue(aCx);
+  {
+    JSONStringWriteFunc<nsCString> buffer;
+    JSONWriter writer(buffer, JSONWriter::SingleLineStyle);
+    profiler_write_active_configuration(writer);
+    NS_ConvertUTF8toUTF16 buffer16(buffer.StringCRef());
+    MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx,
+                                 static_cast<const char16_t*>(buffer16.get()),
+                                 buffer16.Length(), &jsValue));
+  }
+  if (jsValue.isNull()) {
+    aResult.setNull();
+  } else {
+    JS::Rooted<JSObject*> obj(aCx, &jsValue.toObject());
+    if (!obj) {
+      return NS_ERROR_FAILURE;
+    }
+    aResult.setObject(*obj);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::DumpProfileToFile(const char* aFilename) {
+  profiler_save_profile_to_file(aFilename);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileData(double aSinceTime, JSContext* aCx,
+                           JS::MutableHandle<JS::Value> aResult) {
+  mozilla::UniquePtr<char[]> profile = profiler_get_profile(aSinceTime);
+  if (!profile) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ConvertUTF8toUTF16 js_string(nsDependentCString(profile.get()));
+  auto profile16 = static_cast<const char16_t*>(js_string.get());
+
+  JS::Rooted<JS::Value> val(aCx);
+  MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx, profile16, js_string.Length(), &val));
+
+  aResult.set(val);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsync(double aSinceTime, JSContext* aCx,
+                                Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+
+            // Now parse the JSON so that we resolve with a JS Object.
+            JS::Rooted<JS::Value> val(cx);
+            {
+              NS_ConvertUTF8toUTF16 js_string(aResult.mProfile);
+              if (!JS_ParseJSON(cx,
+                                static_cast<const char16_t*>(js_string.get()),
+                                js_string.Length(), &val)) {
+                if (!jsapi.HasException()) {
+                  promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+                } else {
+                  JS::Rooted<JS::Value> exn(cx);
+                  DebugOnly<bool> gotException = jsapi.StealException(&exn);
+                  MOZ_ASSERT(gotException);
+
+                  jsapi.ClearException();
+                  promise->MaybeReject(exn);
+                }
+              } else {
+                promise->MaybeResolve(val);
+              }
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsArrayBuffer(double aSinceTime, JSContext* aCx,
+                                        Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+            JSObject* typedArray = dom::ArrayBuffer::Create(
+                cx, aResult.mProfile.Length(),
+                reinterpret_cast<const uint8_t*>(aResult.mProfile.Data()));
+            if (typedArray) {
+              JS::Rooted<JS::Value> val(cx, JS::ObjectValue(*typedArray));
+              promise->MaybeResolve(val);
+            } else {
+              promise->MaybeReject(NS_ERROR_OUT_OF_MEMORY);
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+nsresult CompressString(const nsCString& aString,
+                        FallibleTArray<uint8_t>& aOutBuff) {
+  // Compress a buffer via zlib (as with `compress()`), but emit a
+  // gzip header as well. Like `compress()`, this is limited to 4GB in
+  // size, but that shouldn't be an issue for our purposes.
+  uLongf outSize = compressBound(aString.Length());
+  if (!aOutBuff.SetLength(outSize, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  int zerr;
+  z_stream stream;
+  stream.zalloc = nullptr;
+  stream.zfree = nullptr;
+  stream.opaque = nullptr;
+  stream.next_out = (Bytef*)aOutBuff.Elements();
+  stream.avail_out = aOutBuff.Length();
+  stream.next_in = (z_const Bytef*)aString.Data();
+  stream.avail_in = aString.Length();
+
+  // A windowBits of 31 is the default (15) plus 16 for emitting a
+  // gzip header; a memLevel of 8 is the default.
+  zerr =
+      deflateInit2(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+                   /* windowBits */ 31, /* memLevel */ 8, Z_DEFAULT_STRATEGY);
+  if (zerr != Z_OK) {
+    return NS_ERROR_FAILURE;
+  }
+
+  zerr = deflate(&stream, Z_FINISH);
+  outSize = stream.total_out;
+  deflateEnd(&stream);
+
+  if (zerr != Z_STREAM_END) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aOutBuff.TruncateLength(outSize);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsGzippedArrayBuffer(double aSinceTime,
+                                               JSContext* aCx,
+                                               Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            FallibleTArray<uint8_t> outBuff;
+            nsresult result = CompressString(aResult.mProfile, outBuff);
+
+            if (result != NS_OK) {
+              promise->MaybeReject(result);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+            // Get the profile typedArray.
+            JSObject* typedArray = dom::ArrayBuffer::Create(
+                cx, outBuff.Length(), outBuff.Elements());
+            if (!typedArray) {
+              promise->MaybeReject(NS_ERROR_OUT_OF_MEMORY);
+              return;
+            }
+            JS::Rooted<JS::Value> typedArrayValue(cx,
+                                                  JS::ObjectValue(*typedArray));
+            // Get the additional information object.
+            JS::Rooted<JS::Value> additionalInfoVal(cx);
+            if (aResult.mAdditionalInformation.isSome()) {
+              aResult.mAdditionalInformation->ToJSValue(cx, &additionalInfoVal);
+            } else {
+              additionalInfoVal.setUndefined();
+            }
+
+            // Create the return object.
+            JS::Rooted<JSObject*> resultObj(cx, JS_NewPlainObject(cx));
+            JS_SetProperty(cx, resultObj, "profile", typedArrayValue);
+            JS_SetProperty(cx, resultObj, "additionalInformation",
+                           additionalInfoVal);
+            promise->MaybeResolve(resultObj);
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::DumpProfileToFileAsync(const nsACString& aFilename,
+                                   double aSinceTime, JSContext* aCx,
+                                   Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  nsCString filename(aFilename);
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [filename,
+           promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            if (aResult.mProfile.Length() >=
+                size_t(std::numeric_limits<std::streamsize>::max())) {
+              promise->MaybeReject(NS_ERROR_FILE_TOO_BIG);
+              return;
+            }
+
+            std::ofstream stream;
+            stream.open(filename.get());
+            if (!stream.is_open()) {
+              promise->MaybeReject(NS_ERROR_FILE_UNRECOGNIZED_PATH);
+              return;
+            }
+
+            stream.write(aResult.mProfile.get(),
+                         std::streamsize(aResult.mProfile.Length()));
+            stream.close();
+
+            promise->MaybeResolveWithUndefined();
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetSymbolTable(const nsACString& aDebugPath,
+                           const nsACString& aBreakpadID, JSContext* aCx,
+                           Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject =
+      xpc::NativeGlobal(JS::CurrentGlobalOrNull(aCx));
+
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  GetSymbolTableMozPromise(aDebugPath, aBreakpadID)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const SymbolTable& aSymbolTable) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+
+            JS::Rooted<JSObject*> addrsArray(
+                cx, dom::Uint32Array::Create(cx, aSymbolTable.mAddrs.Length(),
+                                             aSymbolTable.mAddrs.Elements()));
+            JS::Rooted<JSObject*> indexArray(
+                cx, dom::Uint32Array::Create(cx, aSymbolTable.mIndex.Length(),
+                                             aSymbolTable.mIndex.Elements()));
+            JS::Rooted<JSObject*> bufferArray(
+                cx, dom::Uint8Array::Create(cx, aSymbolTable.mBuffer.Length(),
+                                            aSymbolTable.mBuffer.Elements()));
+
+            if (addrsArray && indexArray && bufferArray) {
+              JS::Rooted<JSObject*> tuple(cx, JS::NewArrayObject(cx, 3));
+              JS_SetElement(cx, tuple, 0, addrsArray);
+              JS_SetElement(cx, tuple, 1, indexArray);
+              JS_SetElement(cx, tuple, 2, bufferArray);
+              promise->MaybeResolve(tuple);
+            } else {
+              promise->MaybeReject(NS_ERROR_FAILURE);
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetElapsedTime(double* aElapsedTime) {
+  *aElapsedTime = profiler_time();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::IsActive(bool* aIsActive) {
+  *aIsActive = profiler_is_active();
+  return NS_OK;
+}
+
+static void GetArrayOfStringsForFeatures(uint32_t aFeatures,
+                                         nsTArray<nsCString>& aFeatureList) {
+#define COUNT_IF_SET(n_, str_, Name_, desc_)    \
+  if (ProfilerFeature::Has##Name_(aFeatures)) { \
+    len++;                                      \
+  }
+
+  // Count the number of features in use.
+  uint32_t len = 0;
+  PROFILER_FOR_EACH_FEATURE(COUNT_IF_SET)
+
+#undef COUNT_IF_SET
+
+  aFeatureList.SetCapacity(len);
+
+#define DUP_IF_SET(n_, str_, Name_, desc_)      \
+  if (ProfilerFeature::Has##Name_(aFeatures)) { \
+    aFeatureList.AppendElement(str_);           \
+  }
+
+  // Insert the strings for the features in use.
+  PROFILER_FOR_EACH_FEATURE(DUP_IF_SET)
+
+#undef DUP_IF_SET
+}
+
+NS_IMETHODIMP
+nsProfiler::GetFeatures(nsTArray<nsCString>& aFeatureList) {
+  uint32_t features = profiler_get_available_features();
+  GetArrayOfStringsForFeatures(features, aFeatureList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetAllFeatures(nsTArray<nsCString>& aFeatureList) {
+  GetArrayOfStringsForFeatures((uint32_t)-1, aFeatureList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetBufferInfo(uint32_t* aCurrentPosition, uint32_t* aTotalSize,
+                          uint32_t* aGeneration) {
+  MOZ_ASSERT(aCurrentPosition);
+  MOZ_ASSERT(aTotalSize);
+  MOZ_ASSERT(aGeneration);
+  Maybe<ProfilerBufferInfo> info = profiler_get_buffer_info();
+  if (info) {
+    *aCurrentPosition = info->mRangeEnd % info->mEntryCount;
+    *aTotalSize = info->mEntryCount;
+    *aGeneration = info->mRangeEnd / info->mEntryCount;
+  } else {
+    *aCurrentPosition = 0;
+    *aTotalSize = 0;
+    *aGeneration = 0;
+  }
+  return NS_OK;
+}
+
+bool nsProfiler::SendProgressRequest(PendingProfile& aPendingProfile) {
+  RefPtr<ProfilerParent::SingleProcessProgressPromise> progressPromise =
+      ProfilerParent::RequestGatherProfileProgress(aPendingProfile.childPid);
+  if (!progressPromise) {
+    LOG("RequestGatherProfileProgress(%u) -> null!",
+        unsigned(aPendingProfile.childPid));
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(
+          Json::StaticString{"Failed to send progress request to pid:"});
+      aEvent.append(Json::Value::UInt64(aPendingProfile.childPid));
+    });
+    // Failed to send request.
+    return false;
+  }
+
+  DEBUG_LOG("RequestGatherProfileProgress(%u) sent...",
+            unsigned(aPendingProfile.childPid));
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{"Requested progress from pid:"});
+    aEvent.append(Json::Value::UInt64(aPendingProfile.childPid));
+  });
+  aPendingProfile.lastProgressRequest = TimeStamp::Now();
+  progressPromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [self = RefPtr<nsProfiler>(this),
+       childPid = aPendingProfile.childPid](GatherProfileProgress&& aResult) {
+        if (!self->mGathering) {
+          return;
+        }
+        PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+        DEBUG_LOG(
+            "RequestGatherProfileProgress(%u) response: %.2f '%s' "
+            "(%u were pending, %s %u)",
+            unsigned(childPid),
+            ProportionValue::FromUnderlyingType(
+                aResult.progressProportionValueUnderlyingType())
+                    .ToDouble() *
+                100.0,
+            aResult.progressLocation().Data(),
+            unsigned(self->mPendingProfiles.length()),
+            pendingProfile ? "including" : "excluding", unsigned(childPid));
+        self->LogEvent([&](Json::Value& aEvent) {
+          aEvent.append(
+              Json::StaticString{"Got response from pid, with progress:"});
+          aEvent.append(Json::Value::UInt64(childPid));
+          aEvent.append(
+              Json::Value{ProportionValue::FromUnderlyingType(
+                              aResult.progressProportionValueUnderlyingType())
+                              .ToDouble() *
+                          100.0});
+        });
+        if (pendingProfile) {
+          // We have a progress report for a still-pending profile.
+          pendingProfile->lastProgressResponse = TimeStamp::Now();
+          // Has it actually made progress?
+          if (aResult.progressProportionValueUnderlyingType() !=
+              pendingProfile->progressProportion.ToUnderlyingType()) {
+            pendingProfile->lastProgressChange =
+                pendingProfile->lastProgressResponse;
+            pendingProfile->progressProportion =
+                ProportionValue::FromUnderlyingType(
+                    aResult.progressProportionValueUnderlyingType());
+            pendingProfile->progressLocation = aResult.progressLocation();
+            self->RestartGatheringTimer();
+          }
+        }
+      },
+      [self = RefPtr<nsProfiler>(this), childPid = aPendingProfile.childPid](
+          ipc::ResponseRejectReason&& aReason) {
+        if (!self->mGathering) {
+          return;
+        }
+        PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+        LOG("RequestGatherProfileProgress(%u) rejection: %d "
+            "(%u were pending, %s %u)",
+            unsigned(childPid), (int)aReason,
+            unsigned(self->mPendingProfiles.length()),
+            pendingProfile ? "including" : "excluding", unsigned(childPid));
+        self->LogEvent([&](Json::Value& aEvent) {
+          aEvent.append(Json::StaticString{
+              "Got progress request rejection from pid, with reason:"});
+          aEvent.append(Json::Value::UInt64(childPid));
+          aEvent.append(Json::Value::UInt{static_cast<unsigned>(aReason)});
+        });
+        if (pendingProfile) {
+          // Failure response, assume the child process is gone.
+          MOZ_ASSERT(self->mPendingProfiles.begin() <= pendingProfile &&
+                     pendingProfile < self->mPendingProfiles.end());
+          self->mPendingProfiles.erase(pendingProfile);
+          if (self->mPendingProfiles.empty()) {
+            // We've got all of the async profiles now. Let's finish off the
+            // profile and resolve the Promise.
+            self->FinishGathering();
+          }
+        }
+      });
+  return true;
+}
+
+/* static */ void nsProfiler::GatheringTimerCallback(nsITimer* aTimer,
+                                                     void* aClosure) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  nsCOMPtr<nsIProfiler> profiler(
+      do_GetService("@mozilla.org/tools/profiler;1"));
+  if (!profiler) {
+    // No (more) profiler service.
+    return;
+  }
+  nsProfiler* self = static_cast<nsProfiler*>(profiler.get());
+  if (self != aClosure) {
+    // Different service object!?
+    return;
+  }
+  if (aTimer != self->mGatheringTimer) {
+    // This timer was cancelled after this callback was queued.
+    return;
+  }
+
+  bool progressWasMade = false;
+
+  // Going backwards, it's easier and cheaper to erase elements if needed.
+  for (auto iPlus1 = self->mPendingProfiles.length(); iPlus1 != 0; --iPlus1) {
+    PendingProfile& pendingProfile = self->mPendingProfiles[iPlus1 - 1];
+
+    bool needToSendProgressRequest = false;
+    if (pendingProfile.lastProgressRequest.IsNull()) {
+      DEBUG_LOG("GatheringTimerCallback() - child %u: No data yet",
+                unsigned(pendingProfile.childPid));
+      // First time going through the list, send an initial progress request.
+      needToSendProgressRequest = true;
+      // We pretend that progress was made, so we don't give up yet.
+      progressWasMade = true;
+    } else if (pendingProfile.lastProgressResponse.IsNull()) {
+      LOG("GatheringTimerCallback() - child %u: Waiting for first response",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for the first response, no progress made here, don't send
+      // another request.
+    } else if (pendingProfile.lastProgressResponse <=
+               pendingProfile.lastProgressRequest) {
+      LOG("GatheringTimerCallback() - child %u: Waiting for response",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for a response to the last request, no progress made
+      // here, don't send another request.
+    } else if (pendingProfile.lastProgressChange.IsNull()) {
+      LOG("GatheringTimerCallback() - child %u: Still waiting for first change",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for the first change, no progress made here, but send a
+      // new request.
+      needToSendProgressRequest = true;
+    } else if (pendingProfile.lastProgressRequest <
+               pendingProfile.lastProgressChange) {
+      DEBUG_LOG("GatheringTimerCallback() - child %u: Recent change",
+                unsigned(pendingProfile.childPid));
+      // We have a recent change, progress was made.
+      needToSendProgressRequest = true;
+      progressWasMade = true;
+    } else {
+      LOG("GatheringTimerCallback() - child %u: No recent change",
+          unsigned(pendingProfile.childPid));
+      needToSendProgressRequest = true;
+    }
+
+    // And send a new progress request.
+    if (needToSendProgressRequest) {
+      if (!self->SendProgressRequest(pendingProfile)) {
+        // Failed to even send the request, consider this process gone.
+        self->mPendingProfiles.erase(&pendingProfile);
+        LOG("... Failed to send progress request");
+      } else {
+        DEBUG_LOG("... Sent progress request");
+      }
+    } else {
+      DEBUG_LOG("... No progress request");
+    }
+  }
+
+  if (self->mPendingProfiles.empty()) {
+    // We've got all of the async profiles now. Let's finish off the profile
+    // and resolve the Promise.
+    self->FinishGathering();
+    return;
+  }
+
+  // Not finished yet.
+
+  if (progressWasMade) {
+    // We made some progress, just restart the timer.
+    DEBUG_LOG("GatheringTimerCallback() - Progress made, restart timer");
+    self->RestartGatheringTimer();
+    return;
+  }
+
+  DEBUG_LOG("GatheringTimerCallback() - Timeout!");
+  self->mGatheringTimer = nullptr;
+  if (!profiler_is_active() || !self->mGathering) {
+    // Not gathering anymore.
+    return;
+  }
+  self->LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{
+        "No progress made recently, giving up; pending pids:"});
+    for (const PendingProfile& pendingProfile : self->mPendingProfiles) {
+      aEvent.append(Json::Value::UInt64(pendingProfile.childPid));
+    }
+  });
+  NS_WARNING("Profiler failed to gather profiles from all sub-processes");
+  // We have really reached a timeout while gathering, finish now.
+  // TODO: Add information about missing processes.
+  self->FinishGathering();
+}
+
+void nsProfiler::RestartGatheringTimer() {
+  if (mGatheringTimer) {
+    uint32_t delayMs = 0;
+    const nsresult r = mGatheringTimer->GetDelay(&delayMs);
+    mGatheringTimer->Cancel();
+    if (NS_FAILED(r) || delayMs == 0 ||
+        NS_FAILED(mGatheringTimer->InitWithNamedFuncCallback(
+            GatheringTimerCallback, this, delayMs,
+            nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY,
+            "nsProfilerGatheringTimer"))) {
+      // Can't restart the timer, so we can't wait any longer.
+      FinishGathering();
+    }
+  }
+}
+
+nsProfiler::PendingProfile* nsProfiler::GetPendingProfile(
+    base::ProcessId aChildPid) {
+  for (PendingProfile& pendingProfile : mPendingProfiles) {
+    if (pendingProfile.childPid == aChildPid) {
+      return &pendingProfile;
+    }
+  }
+  return nullptr;
+}
+
+void nsProfiler::GatheredOOPProfile(
+    base::ProcessId aChildPid, const nsACString& aProfile,
+    mozilla::Maybe<ProfileGenerationAdditionalInformation>&&
+        aAdditionalInformation) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return;
+  }
+
+  if (!mGathering) {
+    // If we're not actively gathering, then we don't actually care that we
+    // gathered a profile here. This can happen for processes that exit while
+    // profiling.
+    return;
+  }
+
+  MOZ_RELEASE_ASSERT(mWriter.isSome(),
+                     "Should always have a writer if mGathering is true");
+
+  // Combine all the additional information into a single struct.
+  if (aAdditionalInformation.isSome()) {
+    mProfileGenerationAdditionalInformation->Append(
+        std::move(*aAdditionalInformation));
+  }
+
+  if (!aProfile.IsEmpty()) {
+    if (mWriter->ChunkedWriteFunc().Length() + aProfile.Length() <
+        scLengthAccumulationThreshold) {
+      // TODO: Remove PromiseFlatCString, see bug 1657033.
+      mWriter->Splice(PromiseFlatCString(aProfile));
+    } else {
+      LogEvent([&](Json::Value& aEvent) {
+        aEvent.append(
+            Json::StaticString{"Discarded child profile that would make the "
+                               "full profile too big, pid and size:"});
+        aEvent.append(Json::Value::UInt64(aChildPid));
+        aEvent.append(Json::Value::UInt64{aProfile.Length()});
+      });
+    }
+  }
+
+  if (PendingProfile* pendingProfile = GetPendingProfile(aChildPid);
+      pendingProfile) {
+    mPendingProfiles.erase(pendingProfile);
+
+    if (mPendingProfiles.empty()) {
+      // We've got all of the async profiles now. Let's finish off the profile
+      // and resolve the Promise.
+      FinishGathering();
+    }
+  }
+
+  // Not finished yet, restart the timer to let any remaining child enough time
+  // to do their profile-streaming.
+  RestartGatheringTimer();
+}
+
+RefPtr<nsProfiler::GatheringPromiseAndroid>
+nsProfiler::GetProfileDataAsGzippedArrayBufferAndroid(double aSinceTime) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return GatheringPromiseAndroid::CreateAndReject(NS_ERROR_FAILURE, __func__);
+  }
+
+  return StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            FallibleTArray<uint8_t> outBuff;
+            nsresult result = CompressString(aResult.mProfile, outBuff);
+            if (result != NS_OK) {
+              return GatheringPromiseAndroid::CreateAndReject(result, __func__);
+            }
+            return GatheringPromiseAndroid::CreateAndResolve(std::move(outBuff),
+                                                             __func__);
+          },
+          [](nsresult aRv) {
+            return GatheringPromiseAndroid::CreateAndReject(aRv, __func__);
+          });
+}
+
+RefPtr<nsProfiler::GatheringPromise> nsProfiler::StartGathering(
+    double aSinceTime) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  if (mGathering) {
+    // If we're already gathering, return a rejected promise - this isn't
+    // going to end well.
+    return GatheringPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE, __func__);
+  }
+
+  mGathering = true;
+  mGatheringLog = mozilla::MakeUnique<Json::Value>(Json::objectValue);
+  (*mGatheringLog)[Json::StaticString{
+      "profileGatheringLogBegin" TIMESTAMP_JSON_SUFFIX}] =
+      ProfilingLog::Timestamp();
+
+  if (mGatheringTimer) {
+    mGatheringTimer->Cancel();
+    mGatheringTimer = nullptr;
+  }
+
+  // Start building shared library info starting from the current process.
+  mProfileGenerationAdditionalInformation.emplace(
+      SharedLibraryInfo::GetInfoForSelf());
+
+  // Request profiles from the other processes. This will trigger asynchronous
+  // calls to ProfileGatherer::GatheredOOPProfile as the profiles arrive.
+  //
+  // Do this before the call to profiler_stream_json_for_this_process() because
+  // that call is slow and we want to let the other processes grab their
+  // profiles as soon as possible.
+  nsTArray<ProfilerParent::SingleProcessProfilePromiseAndChildPid> profiles =
+      ProfilerParent::GatherProfiles();
+
+  MOZ_ASSERT(mPendingProfiles.empty());
+  if (!mPendingProfiles.reserve(profiles.Length())) {
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return GatheringPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
+  }
+
+  mFailureLatchSource.emplace();
+  mWriter.emplace(*mFailureLatchSource);
+
+  UniquePtr<ProfilerCodeAddressService> service =
+      profiler_code_address_service_for_presymbolication();
+
+  // Start building up the JSON result and grab the profile from this process.
+  mWriter->Start();
+  auto rv = profiler_stream_json_for_this_process(*mWriter, aSinceTime,
+                                                  /* aIsShuttingDown */ false,
+                                                  service.get());
+  if (rv.isErr()) {
+    // The profiler is inactive. This either means that it was inactive even
+    // at the time that ProfileGatherer::Start() was called, or that it was
+    // stopped on a different thread since that call. Either way, we need to
+    // reject the promise and stop gathering.
+    ResetGathering(NS_ERROR_NOT_AVAILABLE);
+    return GatheringPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE, __func__);
+  }
+
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(
+        Json::StaticString{"Generated parent process profile, size:"});
+    aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+  });
+
+  mWriter->StartArrayProperty("processes");
+
+  // If we have any process exit profiles, add them immediately.
+  if (Vector<nsCString> exitProfiles = profiler_move_exit_profiles();
+      !exitProfiles.empty()) {
+    for (auto& exitProfile : exitProfiles) {
+      if (!exitProfile.IsEmpty()) {
+        if (exitProfile[0] == '*') {
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(
+                Json::StaticString{"Exit non-profile with error message:"});
+            aEvent.append(exitProfile.Data() + 1);
+          });
+        } else if (mWriter->ChunkedWriteFunc().Length() + exitProfile.Length() <
+                   scLengthAccumulationThreshold) {
+          mWriter->Splice(exitProfile);
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(Json::StaticString{"Added exit profile with size:"});
+            aEvent.append(Json::Value::UInt64{exitProfile.Length()});
+          });
+        } else {
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(
+                Json::StaticString{"Discarded an exit profile that would make "
+                                   "the full profile too big, size:"});
+            aEvent.append(Json::Value::UInt64{exitProfile.Length()});
+          });
+        }
+      }
+    }
+
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(Json::StaticString{
+          "Processed all exit profiles, total size so far:"});
+      aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+    });
+  } else {
+    // There are no pending profiles, we're already done.
+    LogEventLiteralString("No exit profiles.");
+  }
+
+  mPromiseHolder.emplace();
+  RefPtr<GatheringPromise> promise = mPromiseHolder->Ensure(__func__);
+
+  // Keep the array property "processes" and the root object in mWriter open
+  // until FinishGathering() is called. As profiles from the other processes
+  // come in, they will be inserted and end up in the right spot.
+  // FinishGathering() will close the array and the root object.
+
+  if (!profiles.IsEmpty()) {
+    // There *are* pending profiles, let's add handlers for their promises.
+
+    // This timeout value is used to monitor progress while gathering child
+    // profiles. The timer will be restarted after we receive a response with
+    // any progress.
+    constexpr uint32_t cMinChildTimeoutS = 1u;  // 1 second minimum and default.
+    constexpr uint32_t cMaxChildTimeoutS = 60u;  // 1 minute max.
+    uint32_t childTimeoutS = Preferences::GetUint(
+        "devtools.performance.recording.child.timeout_s", cMinChildTimeoutS);
+    if (childTimeoutS < cMinChildTimeoutS) {
+      childTimeoutS = cMinChildTimeoutS;
+    } else if (childTimeoutS > cMaxChildTimeoutS) {
+      childTimeoutS = cMaxChildTimeoutS;
+    }
+    const uint32_t childTimeoutMs = childTimeoutS * PR_MSEC_PER_SEC;
+    Unused << NS_NewTimerWithFuncCallback(
+        getter_AddRefs(mGatheringTimer), GatheringTimerCallback, this,
+        childTimeoutMs, nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY,
+        "nsProfilerGatheringTimer", GetMainThreadSerialEventTarget());
+
+    MOZ_ASSERT(mPendingProfiles.capacity() >= profiles.Length());
+    for (const auto& profile : profiles) {
+      mPendingProfiles.infallibleAppend(PendingProfile{profile.childPid});
+      LogEvent([&](Json::Value& aEvent) {
+        aEvent.append(Json::StaticString{"Waiting for pending profile, pid:"});
+        aEvent.append(Json::Value::UInt64(profile.childPid));
+      });
+      profile.profilePromise->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [self = RefPtr<nsProfiler>(this), childPid = profile.childPid](
+              IPCProfileAndAdditionalInformation&& aResult) {
+            PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+            mozilla::ipc::Shmem profileShmem = aResult.profileShmem();
+            LOG("GatherProfile(%u) response: %u bytes (%u were pending, %s %u)",
+                unsigned(childPid), unsigned(profileShmem.Size<char>()),
+                unsigned(self->mPendingProfiles.length()),
+                pendingProfile ? "including" : "excluding", unsigned(childPid));
+            if (profileShmem.IsReadable()) {
+              self->LogEvent([&](Json::Value& aEvent) {
+                aEvent.append(
+                    Json::StaticString{"Got profile from pid, with size:"});
+                aEvent.append(Json::Value::UInt64(childPid));
+                aEvent.append(Json::Value::UInt64{profileShmem.Size<char>()});
+              });
+              const nsDependentCSubstring profileString(
+                  profileShmem.get<char>(), profileShmem.Size<char>() - 1);
+              if (profileString.IsEmpty() || profileString[0] != '*') {
+                self->GatheredOOPProfile(
+                    childPid, profileString,
+                    std::move(aResult.additionalInformation()));
+              } else {
+                self->LogEvent([&](Json::Value& aEvent) {
+                  aEvent.append(Json::StaticString{
+                      "Child non-profile from pid, with error message:"});
+                  aEvent.append(Json::Value::UInt64(childPid));
+                  aEvent.append(profileString.Data() + 1);
+                });
+                self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+              }
+            } else {
+              // This can happen if the child failed to allocate
+              // the Shmem (or maliciously sent an invalid Shmem).
+              self->LogEvent([&](Json::Value& aEvent) {
+                aEvent.append(Json::StaticString{"Got failure from pid:"});
+                aEvent.append(Json::Value::UInt64(childPid));
+              });
+              self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+            }
+          },
+          [self = RefPtr<nsProfiler>(this),
+           childPid = profile.childPid](ipc::ResponseRejectReason&& aReason) {
+            PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+            LOG("GatherProfile(%u) rejection: %d (%u were pending, %s %u)",
+                unsigned(childPid), (int)aReason,
+                unsigned(self->mPendingProfiles.length()),
+                pendingProfile ? "including" : "excluding", unsigned(childPid));
+            self->LogEvent([&](Json::Value& aEvent) {
+              aEvent.append(
+                  Json::StaticString{"Got rejection from pid, with reason:"});
+              aEvent.append(Json::Value::UInt64(childPid));
+              aEvent.append(Json::Value::UInt{static_cast<unsigned>(aReason)});
+            });
+            self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+          });
+    }
+  } else {
+    // There are no pending profiles, we're already done.
+    LogEventLiteralString("No pending child profiles.");
+    FinishGathering();
+  }
+
+  return promise;
+}
+
+RefPtr<nsProfiler::SymbolTablePromise> nsProfiler::GetSymbolTableMozPromise(
+    const nsACString& aDebugPath, const nsACString& aBreakpadID) {
+  MozPromiseHolder<SymbolTablePromise> promiseHolder;
+  RefPtr<SymbolTablePromise> promise = promiseHolder.Ensure(__func__);
+
+  if (!mSymbolTableThread) {
+    nsresult rv = NS_NewNamedThread("ProfSymbolTable",
+                                    getter_AddRefs(mSymbolTableThread));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+      return promise;
+    }
+  }
+
+  nsresult rv = mSymbolTableThread->Dispatch(NS_NewRunnableFunction(
+      "nsProfiler::GetSymbolTableMozPromise runnable on ProfSymbolTable thread",
+      [promiseHolder = std::move(promiseHolder),
+       debugPath = nsCString(aDebugPath),
+       breakpadID = nsCString(aBreakpadID)]() mutable {
+        AUTO_PROFILER_LABEL_DYNAMIC_NSCSTRING("profiler_get_symbol_table",
+                                              OTHER, debugPath);
+        SymbolTable symbolTable;
+        bool succeeded = profiler_get_symbol_table(
+            debugPath.get(), breakpadID.get(), &symbolTable);
+        if (succeeded) {
+          promiseHolder.Resolve(std::move(symbolTable), __func__);
+        } else {
+          promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+        }
+      }));
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Get-symbol task was not dispatched and therefore won't fulfill the
+    // promise, we must reject the promise now.
+    promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+  }
+
+  return promise;
+}
+
+void nsProfiler::FinishGathering() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  MOZ_RELEASE_ASSERT(mWriter.isSome());
+  MOZ_RELEASE_ASSERT(mPromiseHolder.isSome());
+  MOZ_RELEASE_ASSERT(mProfileGenerationAdditionalInformation.isSome());
+
+  // Close the "processes" array property.
+  mWriter->EndArray();
+
+  if (mGatheringLog) {
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(Json::StaticString{"Finished gathering, total size:"});
+      aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+    });
+    (*mGatheringLog)[Json::StaticString{
+        "profileGatheringLogEnd" TIMESTAMP_JSON_SUFFIX}] =
+        ProfilingLog::Timestamp();
+    mWriter->StartObjectProperty("profileGatheringLog");
+    {
+      nsAutoCString pid;
+      pid.AppendInt(int64_t(profiler_current_process_id().ToNumber()));
+      Json::String logString = ToCompactString(*mGatheringLog);
+      mGatheringLog = nullptr;
+      mWriter->SplicedJSONProperty(pid, logString);
+    }
+    mWriter->EndObject();
+  }
+
+  // Close the root object of the generated JSON.
+  mWriter->End();
+
+  if (const char* failure = mWriter->GetFailure(); failure) {
+#ifndef ANDROID
+    fprintf(stderr, "JSON generation failure: %s", failure);
+#else
+    __android_log_print(ANDROID_LOG_INFO, "GeckoProfiler",
+                        "JSON generation failure: %s", failure);
+#endif
+    NS_WARNING("Error during JSON generation, probably OOM.");
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+
+  // And try to resolve the promise with the profile JSON.
+  const size_t len = mWriter->ChunkedWriteFunc().Length();
+  if (len >= scLengthMax) {
+    NS_WARNING("Profile JSON is too big to fit in a string.");
+    ResetGathering(NS_ERROR_FILE_TOO_BIG);
+    return;
+  }
+
+  nsCString result;
+  if (!result.SetLength(len, fallible)) {
+    NS_WARNING("Cannot allocate a string for the Profile JSON.");
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+  MOZ_ASSERT(*(result.Data() + len) == '\0',
+             "We expected a null at the end of the string buffer, to be "
+             "rewritten by CopyDataIntoLazilyAllocatedBuffer");
+
+  char* const resultBeginWriting = result.BeginWriting();
+  if (!resultBeginWriting) {
+    NS_WARNING("Cannot access the string to write the Profile JSON.");
+    ResetGathering(NS_ERROR_CACHE_WRITE_ACCESS_DENIED);
+    return;
+  }
+
+  // Here, we have enough space reserved in `result`, starting at
+  // `resultBeginWriting`, copy the JSON profile there.
+  if (!mWriter->ChunkedWriteFunc().CopyDataIntoLazilyAllocatedBuffer(
+          [&](size_t aBufferLen) -> char* {
+            MOZ_RELEASE_ASSERT(aBufferLen == len + 1);
+            return resultBeginWriting;
+          })) {
+    NS_WARNING("Could not copy profile JSON, probably OOM.");
+    ResetGathering(NS_ERROR_FILE_TOO_BIG);
+    return;
+  }
+  MOZ_ASSERT(*(result.Data() + len) == '\0',
+             "We still expected a null at the end of the string buffer");
+
+  mProfileGenerationAdditionalInformation->FinishGathering();
+  mPromiseHolder->Resolve(
+      ProfileAndAdditionalInformation{
+          std::move(result),
+          std::move(*mProfileGenerationAdditionalInformation)},
+      __func__);
+
+  ResetGathering(NS_ERROR_UNEXPECTED);
+}
+
+void nsProfiler::ResetGathering(nsresult aPromiseRejectionIfPending) {
+  // If we have an unfulfilled Promise in flight, we should reject it before
+  // destroying the promise holder.
+  if (mPromiseHolder.isSome()) {
+    mPromiseHolder->RejectIfExists(aPromiseRejectionIfPending, __func__);
+    mPromiseHolder.reset();
+  }
+  mPendingProfiles.clearAndFree();
+  mGathering = false;
+  mGatheringLog = nullptr;
+  if (mGatheringTimer) {
+    mGatheringTimer->Cancel();
+    mGatheringTimer = nullptr;
+  }
+  mWriter.reset();
+  mFailureLatchSource.reset();
+  mProfileGenerationAdditionalInformation.reset();
+}