Bug 1551992 - Compress profile data before sending to perf-html; r=mstange,julienw

Differential Revision: https://phabricator.services.mozilla.com/D33399

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

devtools/client/performance-new/popup/background.jsm

@@ -91,12 +91,11 @@ async function captureProfile() {
   // more samples while the parent process waits for subprocess profiles.
   Services.profiler.PauseSampling();
 
-  const profile = await Services.profiler.getProfileDataAsArrayBuffer().catch(
-    e => {
-      console.error(e);
-      return {};
-    }
-  );
+  const profile = await Services.profiler.getProfileDataAsGzippedArrayBuffer()
+                                .catch(e => {
+                                  console.error(e);
+                                  return {};
+                                });
 
   receiveProfile(profile, getSymbols);
 

toolkit/components/extensions/parent/ext-geckoProfiler.js

@@ -122,6 +122,15 @@ this.geckoProfiler = class extends ExtensionAPI {
           return Services.profiler.getProfileDataAsArrayBuffer();
         },
 
+        async getProfileAsGzippedArrayBuffer() {
+          if (!Services.profiler.IsActive()) {
+            throw new ExtensionError("The profiler is stopped. " +
+              "You need to start the profiler before you can capture a profile.");
+          }
+
+          return Services.profiler.getProfileDataAsGzippedArrayBuffer();
+        },
+
         async getSymbols(debugName, breakpadId) {
           if (symbolCache.size === 0) {
             primeSymbolStore(Services.profiler.sharedLibraries);

toolkit/components/extensions/schemas/geckoProfiler.json

@@ -126,6 +126,13 @@
         "async": true,
         "parameters": []
       },
+      {
+        "name": "getProfileAsGzippedArrayBuffer",
+        "type": "function",
+        "description": "Gathers the profile data from the current profiling session. The returned promise resolves to an array buffer that contains a gzipped JSON string.",
+        "async": true,
+        "parameters": []
+      },
       {
         "name": "getSymbols",
         "type": "function",

tools/profiler/gecko/nsIProfiler.idl

@@ -62,6 +62,9 @@ interface nsIProfiler : nsISupports
   [implicit_jscontext]
   Promise getProfileDataAsArrayBuffer([optional] in double aSinceTime);
 
+  [implicit_jscontext]
+  Promise getProfileDataAsGzippedArrayBuffer([optional] in double aSinceTime);
+
   /**
    * Returns a promise that resolves once the file has been written.
    */

tools/profiler/gecko/nsProfiler.cpp

@@ -30,6 +30,7 @@
 #include "nsString.h"
 #include "nsThreadUtils.h"
 #include "shared-libraries.h"
+#include "zlib.h"
 
 #include <string>
 #include <sstream>
@@ -372,6 +373,100 @@ nsProfiler::GetProfileDataAsArrayBuffer(double aSinceTime, JSContext* aCx,
   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](nsCString 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;
+            }
+
+            // 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(aResult.Length());
+            FallibleTArray<uint8_t> outBuff;
+            if (!outBuff.SetLength(outSize, fallible)) {
+              promise->MaybeReject(NS_ERROR_OUT_OF_MEMORY);
+              return;
+            }
+
+            int zerr;
+            z_stream stream;
+            stream.zalloc = nullptr;
+            stream.zfree = nullptr;
+            stream.opaque = nullptr;
+            stream.next_out = (Bytef*)outBuff.Elements();
+            stream.avail_out = outBuff.Length();
+            stream.next_in = (z_const Bytef*)aResult.Data();
+            stream.avail_in = aResult.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) {
+              promise->MaybeReject(NS_ERROR_FAILURE);
+              return;
+            }
+
+            zerr = deflate(&stream, Z_FINISH);
+            outSize = stream.total_out;
+            deflateEnd(&stream);
+
+            if (zerr != Z_STREAM_END) {
+              promise->MaybeReject(NS_ERROR_FAILURE);
+              return;
+            }
+
+            outBuff.TruncateLength(outSize);
+
+            JSContext* cx = jsapi.cx();
+            JSObject* typedArray = dom::ArrayBuffer::Create(
+                cx, outBuff.Length(), outBuff.Elements());
+            if (typedArray) {
+              JS::RootedValue 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;
+}
+
 NS_IMETHODIMP
 nsProfiler::DumpProfileToFileAsync(const nsACString& aFilename,
                                    double aSinceTime, JSContext* aCx,