Add ability to take heap snapshots with python debugger

Signed-off-by: Ádám László Kulcsár <adam.kulcsar@szteszoftver.hu>

src/debugger/DebuggerEscargot.cpp

@@ -1002,7 +1002,23 @@ bool DebuggerEscargot::processEvents(ExecutionState* state, Optional<ByteCodeBlo
         }
         case ESCARGOT_DEBUGGER_TAKE_HEAP_SNAPSHOT: {
             HeapSnapshot snapshot;
-            snapshot.takeHeapSnapshot(state);
+            std::string fileName = snapshot.takeHeapSnapshot(state);
+
+            if (fileName.empty()) {
+                ESCARGOT_LOG_ERROR("Error happened during heap snapshot creation. Aborting now.\n");
+                abort();
+            } else if (enabled()) {
+                String* data = String::fromUTF8(fileName.c_str(), fileName.length());
+
+                if (data == nullptr) {
+                    ESCARGOT_LOG_ERROR("Error happened during heap snapshot creation. Aborting now.\n");
+                    abort();
+                }
+
+                send(ESCARGOT_DEBUGGER_SNAPSHOT_FINISHED,
+                     data->characters8(),
+                     data->length());
+            }
             return true;
         }
         }

src/debugger/DebuggerEscargot.h

@@ -97,7 +97,8 @@ public:
         ESCARGOT_MESSAGE_EXCEPTION_BACKTRACE = 46,
         ESCARGOT_DEBUGGER_WAIT_FOR_SOURCE = 47,
         ESCARGOT_DEBUGGER_WAITING_AFTER_PENDING = 48,
-        ESCARGOT_DEBUGGER_WAIT_FOR_WAIT_EXIT = 49
+        ESCARGOT_DEBUGGER_WAIT_FOR_WAIT_EXIT = 49,
+        ESCARGOT_DEBUGGER_SNAPSHOT_FINISHED = 50
     };
 
     // Messages sent by the debugger client to Escargot

src/debugger/HeapSnapshot.cpp

@@ -267,7 +267,7 @@ void HeapSnapshot::addNotIndexedDeclarativeEnvironmentRecord(ExecutionState* sta
     }
 }
 
-bool HeapSnapshot::prepareHeapSnapshotFile()
+std::string HeapSnapshot::prepareHeapSnapshotFile()
 {
     auto addFields = [](rapidjson::Value& array, Vector<std::string, GCUtil::gc_malloc_allocator<std::string>>& strings, rapidjson::Document::AllocatorType& allocator) {
         for (const std::string& elem : strings) {
@@ -431,7 +431,7 @@ bool HeapSnapshot::prepareHeapSnapshotFile()
 
     if (output.get() == nullptr) {
         ESCARGOT_LOG_ERROR("Could not create heap snapshot file.\n");
-        return false;
+        return "";
     }
 
     char buffer[65536];
@@ -439,11 +439,10 @@ bool HeapSnapshot::prepareHeapSnapshotFile()
     rapidjson::Writer<rapidjson::FileWriteStream> writer(os);
     jsonDoc.Accept(writer);
 
-    return true;
+    return outputName;
 }
 
-
-void HeapSnapshot::takeHeapSnapshot(ExecutionState* state)
+std::string HeapSnapshot::takeHeapSnapshot(ExecutionState* state)
 {
     uint64_t id = 0;
     uint64_t stateIdx = 0;
@@ -524,10 +523,7 @@ void HeapSnapshot::takeHeapSnapshot(ExecutionState* state)
     }
 
     ESCARGOT_LOG_INFO("nodes: %ld | edges: %ld | strings: %ld", m_nodeCount, m_edgeCount, m_strings.size());
-    if (prepareHeapSnapshotFile() != true) {
-        ESCARGOT_LOG_ERROR("Error happened during heap snapshot creation. Aborting now.\n");
-        abort();
-    }
+    return prepareHeapSnapshotFile();
 }
 } // namespace Escargot
 #endif

src/debugger/HeapSnapshot.h

@@ -130,8 +130,8 @@ public:
     void addIndexedDeclarativeEnvironmentRecord(ExecutionState* state, DeclarativeEnvironmentRecordIndexed* env, uint64_t& id, uint64_t& LexicalEnvIdx);
     void addNotIndexedDeclarativeEnvironmentRecord(ExecutionState* state, DeclarativeEnvironmentRecordNotIndexed* env, uint64_t& id, uint64_t& LexicalEnvIdx);
 
-    bool prepareHeapSnapshotFile();
-    void takeHeapSnapshot(ExecutionState* state);
+    std::string prepareHeapSnapshotFile();
+    std::string takeHeapSnapshot(ExecutionState* state);
 
 private:
     uint64_t m_nodeCount;

tools/debugger/debugger.py

@@ -197,6 +197,12 @@ class DebuggerPrompt(Cmd):
         self.stop = True
     do_bt = do_backtrace
 
+    def do_take_snapshot(self, args):
+        """ Save heap snapshot to a .snapshot file in the escargot binary's folder """
+        file_name = self.debugger._send_take_snapshot()
+        print("Took heap snapshot as \'" + file_name.decode('utf-8')[1:] + "\'!")
+        self.stop = True
+
     def do_scope(self, args):
         """ Get lexical environment chain """
         self.debugger.scope_chain(args)

tools/debugger/debugger_core.py

@@ -109,7 +109,8 @@ ESCARGOT_DEBUGGER_THERE_WAS_NO_SOURCE = 26
 ESCARGOT_DEBUGGER_PENDING_CONFIG = 27
 ESCARGOT_DEBUGGER_PENDING_RESUME = 28
 ESCARGOT_DEBUGGER_WAIT_BEFORE_EXIT = 29
-ESCARGOT_DEBUGGER_STOP = 30
+ESCARGOT_DEBUGGER_TAKE_HEAP_SNAPSHOT = 30
+ESCARGOT_DEBUGGER_STOP = 31
 
 
 # Environment record types
@@ -626,6 +627,11 @@ class Debugger(object):
                               1 if self.wait_exit else 0)
         self.channel.send_message(self.byte_order, message)
 
+    def _send_take_snapshot(self):
+        message = struct.pack(self.byte_order + "BB", 1, ESCARGOT_DEBUGGER_TAKE_HEAP_SNAPSHOT)
+        self.channel.send_message(self.byte_order, message)
+        return self.channel.get_message(True)
+
     def _exec_command(self, command_id):
         message = struct.pack(self.byte_order + "BB",
                               1,