[heap profiler] Plumb samples through the protocol.

BUG=chromium:889545

Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ic00ffa9968cffaf2e20682e247747b5f7dc0f145
Reviewed-on: https://chromium-review.googlesource.com/c/1285394
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56874}

src/inspector/js_protocol.json

@@ -1188,6 +1188,11 @@
                             "description": "Allocations size in bytes for the node excluding children.",
                             "type": "number"
                         },
+                        {
+                            "name": "id",
+                            "description": "Node id. Ids are unique across all profiles collected between startSampling and stopSampling.",
+                            "type": "integer"
+                        },
                         {
                             "name": "children",
                             "description": "Child nodes.",
@@ -1198,14 +1203,43 @@
                         }
                     ]
                 },
+                {
+                    "id": "SamplingHeapProfileSample",
+                    "description": "A single sample from a sampling profile.",
+                    "type": "object",
+                    "properties": [
+                        {
+                            "name": "size",
+                            "description": "Allocation size in bytes attributed to the sample.",
+                            "type": "number"
+                        },
+                        {
+                            "name": "nodeId",
+                            "description": "Id of the corresponding profile tree node.",
+                            "type": "integer"
+                        },
+                        {
+                            "name": "ordinal",
+                            "description": "Time-ordered sample ordinal number. It is unique across all profiles retrieved\nbetween startSampling and stopSampling.",
+                            "type": "number"
+                        }
+                    ]
+                },
                 {
                     "id": "SamplingHeapProfile",
-                    "description": "Profile.",
+                    "description": "Sampling profile.",
                     "type": "object",
                     "properties": [
                         {
                             "name": "head",
                             "$ref": "SamplingHeapProfileNode"
+                        },
+                        {
+                            "name": "samples",
+                            "type": "array",
+                            "items": {
+                                "$ref": "SamplingHeapProfileSample"
+                            }
                         }
                     ]
                 }

src/inspector/js_protocol.pdl

@@ -556,13 +556,27 @@ experimental domain HeapProfiler
       Runtime.CallFrame callFrame
       # Allocations size in bytes for the node excluding children.
       number selfSize
+      # Node id. Ids are unique across all profiles collected between startSampling and stopSampling.
+      integer id
       # Child nodes.
       array of SamplingHeapProfileNode children
 
-  # Profile.
+  # A single sample from a sampling profile.
+  type SamplingHeapProfileSample extends object
+    properties
+      # Allocation size in bytes attributed to the sample.
+      number size
+      # Id of the corresponding profile tree node.
+      integer nodeId
+      # Time-ordered sample ordinal number. It is unique across all profiles retrieved
+      # between startSampling and stopSampling.
+      number ordinal
+
+  # Sampling profile.
   type SamplingHeapProfile extends object
     properties
       SamplingHeapProfileNode head
+      array of SamplingHeapProfileSample samples
 
   # Enables console to refer to the node with given id via $x (see Command Line API for more details
   # $x functions).

src/inspector/v8-heap-profiler-agent-impl.cc

@@ -357,6 +357,7 @@ buildSampingHeapProfileNode(v8::Isolate* isolate,
           .setCallFrame(std::move(callFrame))
           .setSelfSize(selfSize)
           .setChildren(std::move(children))
+          .setId(node->node_id)
           .build();
   return result;
 }
@@ -376,15 +377,25 @@ Response V8HeapProfilerAgentImpl::stopSampling(
 Response V8HeapProfilerAgentImpl::getSamplingProfile(
     std::unique_ptr<protocol::HeapProfiler::SamplingHeapProfile>* profile) {
   v8::HeapProfiler* profiler = m_isolate->GetHeapProfiler();
-  v8::HandleScope scope(
-      m_isolate);  // v8::AllocationProfile contains Local handles.
+  // Need a scope as v8::AllocationProfile contains Local handles.
+  v8::HandleScope scope(m_isolate);
   std::unique_ptr<v8::AllocationProfile> v8Profile(
       profiler->GetAllocationProfile());
   if (!v8Profile)
     return Response::Error("V8 sampling heap profiler was not started.");
   v8::AllocationProfile::Node* root = v8Profile->GetRootNode();
+  auto samples = protocol::Array<
+      protocol::HeapProfiler::SamplingHeapProfileSample>::create();
+  for (const auto& sample : v8Profile->GetSamples()) {
+    samples->addItem(protocol::HeapProfiler::SamplingHeapProfileSample::create()
+                         .setSize(sample.size * sample.count)
+                         .setNodeId(sample.node_id)
+                         .setOrdinal(static_cast<double>(sample.sample_id))
+                         .build());
+  }
   *profile = protocol::HeapProfiler::SamplingHeapProfile::create()
                  .setHead(buildSampingHeapProfileNode(m_isolate, root))
+                 .setSamples(std::move(samples))
                  .build();
   return Response::OK();
 }

test/inspector/heap-profiler/sampling-heap-profiler-expected.txt

@@ -4,4 +4,5 @@ Allocated size is zero in the beginning: true
 Allocated size is more than 100KB after a chunk is allocated: true
 Allocated size increased after one more chunk is allocated: true
 Allocated size did not change after stopping: true
+Sample found: true
 Successfully finished

test/inspector/heap-profiler/sampling-heap-profiler.js

@@ -38,6 +38,11 @@
   const size4 = nodeSize(profile4.result.profile.head);
   InspectorTest.log('Allocated size did not change after stopping:', size4 === size3);
 
+  const sample = profile4.result.profile.samples.find(s => s.size > 400000);
+  const hasSample = hasNode(n => n.id === sample.nodeId && n.callFrame.functionName === 'allocateChunk',
+                            profile4.result.profile.head);
+  InspectorTest.log('Sample found: ' + hasSample);
+
   InspectorTest.log('Successfully finished');
   InspectorTest.completeTest();
 
@@ -45,4 +50,8 @@
     return node.children.reduce((res, child) => res + nodeSize(child),
                                 node.callFrame.functionName === 'allocateChunk' ? node.selfSize : 0);
   }
+
+  function hasNode(predicate, node) {
+    return predicate(node) || node.children.some(hasNode.bind(null, predicate));
+  }
 })();