1 files changed, 30 insertions, 25 deletions

diff --git a/src/core/lib/channel/channel_trace.h b/src/core/lib/channel/channel_trace.h
index 596af7402f..8ff91ee8c8 100644
--- a/src/core/lib/channel/channel_trace.h
+++ b/src/core/lib/channel/channel_trace.h
@@ -30,14 +30,18 @@
 namespace grpc_core {
 namespace channelz {
 
-class ChannelNode;
+namespace testing {
+size_t GetSizeofTraceEvent(void);
+}
+
+class BaseNode;
 
 // Object used to hold live data for a channel. This data is exposed via the
 // channelz service:
 // https://github.com/grpc/proposal/blob/master/A14-channelz.md
 class ChannelTrace {
  public:
-  ChannelTrace(size_t max_events);
+  ChannelTrace(size_t max_event_memory);
   ~ChannelTrace();
 
   enum Severity {
@@ -49,41 +53,42 @@ class ChannelTrace {
 
   // Adds a new trace event to the tracing object
   //
+  // NOTE: each ChannelTrace tracks the memory used by its list of trace
+  // events, so adding an event with a large amount of data could cause other
+  // trace event to be evicted. If a single trace is larger than the limit, it
+  // will cause all events to be evicted. The limit is set with the arg:
+  // GRPC_ARG_MAX_CHANNEL_TRACE_EVENT_MEMORY_PER_NODE.
+  //
   // TODO(ncteisen): as this call is used more and more throughout the gRPC
   // stack, determine if it makes more sense to accept a char* instead of a
   // slice.
   void AddTraceEvent(Severity severity, grpc_slice data);
 
   // Adds a new trace event to the tracing object. This trace event refers to a
-  // an event on a child of the channel. For example, if this channel has
-  // created a new subchannel, then it would record that with a TraceEvent
-  // referencing the new subchannel.
+  // an event that concerns a different channelz entity. For example, if this
+  // channel has created a new subchannel, then it would record that with
+  // a TraceEvent referencing the new subchannel.
   //
-  // TODO(ncteisen): as this call is used more and more throughout the gRPC
-  // stack, determine if it makes more sense to accept a char* instead of a
-  // slice.
-  void AddTraceEventReferencingChannel(
-      Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelNode> referenced_channel);
-  void AddTraceEventReferencingSubchannel(
-      Severity severity, grpc_slice data,
-      RefCountedPtr<ChannelNode> referenced_subchannel);
+  // NOTE: see the note in the method above.
+  //
+  // TODO(ncteisen): see the todo in the method above.
+  void AddTraceEventWithReference(Severity severity, grpc_slice data,
+                                  RefCountedPtr<BaseNode> referenced_entity);
 
   // Creates and returns the raw grpc_json object, so a parent channelz
   // object may incorporate the json before rendering.
   grpc_json* RenderJson() const;
 
  private:
-  // Types of objects that can be references by trace events.
-  enum class ReferencedType { Channel, Subchannel };
+  friend size_t testing::GetSizeofTraceEvent(void);
+
   // Private class to encapsulate all the data and bookkeeping needed for a
   // a trace event.
   class TraceEvent {
    public:
-    // Constructor for a TraceEvent that references a different channel.
+    // Constructor for a TraceEvent that references a channel.
     TraceEvent(Severity severity, grpc_slice data,
-               RefCountedPtr<ChannelNode> referenced_channel,
-               ReferencedType type);
+               RefCountedPtr<BaseNode> referenced_entity_);
 
     // Constructor for a TraceEvent that does not reverence a different
     // channel.
@@ -99,16 +104,16 @@ class ChannelTrace {
     TraceEvent* next() const { return next_; }
     void set_next(TraceEvent* next) { next_ = next; }
 
+    size_t memory_usage() const { return memory_usage_; }
+
    private:
     Severity severity_;
     grpc_slice data_;
     gpr_timespec timestamp_;
     TraceEvent* next_;
     // the tracer object for the (sub)channel that this trace event refers to.
-    RefCountedPtr<ChannelNode> referenced_channel_;
-    // the type that the referenced tracer points to. Unused if this trace
-    // does not point to any channel or subchannel
-    ReferencedType referenced_type_;
+    RefCountedPtr<BaseNode> referenced_entity_;
+    size_t memory_usage_;
   };  // TraceEvent
 
   // Internal helper to add and link in a trace event
@@ -116,8 +121,8 @@ class ChannelTrace {
 
   gpr_mu tracer_mu_;
   uint64_t num_events_logged_;
-  size_t list_size_;
-  size_t max_list_size_;
+  size_t event_list_memory_usage_;
+  size_t max_event_memory_;
   TraceEvent* head_trace_;
   TraceEvent* tail_trace_;
   gpr_timespec time_created_;