1 files changed, 21 insertions, 6 deletions

diff --git a/src/core/lib/channel/channel_trace.h b/src/core/lib/channel/channel_trace.h
index 94fea20b45..8ff91ee8c8 100644
--- a/src/core/lib/channel/channel_trace.h
+++ b/src/core/lib/channel/channel_trace.h
@@ -30,6 +30,10 @@
 namespace grpc_core {
 namespace channelz {
 
+namespace testing {
+size_t GetSizeofTraceEvent(void);
+}
+
 class BaseNode;
 
 // Object used to hold live data for a channel. This data is exposed via the
@@ -37,7 +41,7 @@ class BaseNode;
 // 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 {
@@ -49,6 +53,12 @@ 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.
@@ -59,9 +69,9 @@ class ChannelTrace {
   // 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.
+  // 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);
 
@@ -70,6 +80,8 @@ class ChannelTrace {
   grpc_json* RenderJson() const;
 
  private:
+  friend size_t testing::GetSizeofTraceEvent(void);
+
   // Private class to encapsulate all the data and bookkeeping needed for a
   // a trace event.
   class TraceEvent {
@@ -92,6 +104,8 @@ 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_;
@@ -99,6 +113,7 @@ class ChannelTrace {
     TraceEvent* next_;
     // the tracer object for the (sub)channel that this trace event refers to.
     RefCountedPtr<BaseNode> referenced_entity_;
+    size_t memory_usage_;
   };  // TraceEvent
 
   // Internal helper to add and link in a trace event
@@ -106,8 +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_;