Per isolate Log with block support

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 31b8c9e147bd5b88ac54da97348e9de717d05e3b..d7a6e591c9abae128c0eef8f7486cc24b359f5ed 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -16,6 +16,7 @@
 #include "vm/deopt_instructions.h"
 #include "vm/heap.h"
 #include "vm/lockers.h"
+#include "vm/log.h"
 #include "vm/message_handler.h"
 #include "vm/object_id_ring.h"
 #include "vm/object_store.h"
@@ -46,7 +47,9 @@ DEFINE_FLAG(bool, pause_isolates_on_exit, false,
 DEFINE_FLAG(bool, break_at_isolate_spawn, false,
             "Insert a one-time breakpoint at the entrypoint for all spawned "
             "isolates");
-
+DEFINE_FLAG(charp, isolate_log_filter, NULL,
+            "Log isolates whose name include the filter. "
+            "Default: service isolate log messages are suppressed.");
 
 // Quick access to the locally defined isolate() method.
 #define I (isolate())
@@ -475,6 +478,8 @@ Isolate::Isolate()
       gc_epilogue_callback_(NULL),
       defer_finalization_count_(0),
       deopt_context_(NULL),
+      is_service_isolate_(false),
+      log_(new class Log()),
       stacktrace_(NULL),
       stack_frame_index_(-1),
       last_allocationprofile_accumulator_reset_timestamp_(0),
@@ -534,6 +539,8 @@ Isolate::Isolate(Isolate* original)
       gc_epilogue_callback_(NULL),
       defer_finalization_count_(0),
       deopt_context_(NULL),
+      is_service_isolate_(false),
+      log_(new class Log()),
       stacktrace_(NULL),
       stack_frame_index_(-1),
       last_allocationprofile_accumulator_reset_timestamp_(0),
@@ -571,6 +578,8 @@ Isolate::~Isolate() {
   message_handler_ = NULL;  // Fail fast if we send messages to a dead isolate.
   ASSERT(deopt_context_ == NULL);  // No deopt in progress when isolate deleted.
   delete spawn_state_;
+  delete log_;
+  log_ = NULL;
 }
 
 
@@ -695,6 +704,23 @@ void Isolate::BuildName(const char* name_prefix) {
 }
 
 
+Log* Isolate::Log() const {
+  if (FLAG_isolate_log_filter == NULL) {
+    if (is_service_isolate_) {
+      // By default, do not log for the service isolate.
+      return Log::NoOpLog();
+    }
+    return log_;
+  }
+  ASSERT(name_ != NULL);
+  if (strstr(name_, FLAG_isolate_log_filter) == NULL) {
+    // Filter does not match, do not log for this isolate.
+    return Log::NoOpLog();
+  }
+  return log_;
+}
+
+
 // TODO(5411455): Use flag to override default value and Validate the
 // stack size by querying OS.
 uword Isolate::GetSpecifiedStackSize() {