Support per shard redis proxy latency per command metrics

Author: gavin-jeong

source/extensions/filters/network/redis_proxy/conn_pool_impl.cc

@@ -597,6 +597,11 @@ InstanceImpl::PendingRequest::PendingRequest(InstanceImpl::ThreadLocalPool& pare
   if (shard_scope_ && parent_.config_->enableCommandStats()) {
     command_ = parent_.redis_command_stats_->getCommandFromRequest(getRequest(incoming_request_));
     parent_.redis_command_stats_->updateStatsTotal(*shard_scope_, command_);
+    // Create per-shard per-command latency timer when both command stats and per-shard latency are enabled
+    if (parent_.config_->enablePerShardLatencyStats()) {
+      command_latency_timer_ = parent_.redis_command_stats_->createCommandTimer(
+          *shard_scope_, command_, parent_.dispatcher_.timeSource());
+    }
   }
 }
 
@@ -639,6 +644,8 @@ void InstanceImpl::PendingRequest::onResponse(Common::Redis::RespValuePtr&& resp
         end_time - start_time_).count();
     latency_histogram_->recordValue(latency_us);
   }
+  // Complete per-shard per-command latency timer (auto-records on destruction)
+  command_latency_timer_.reset();
   pool_callbacks_.onResponse(std::move(response));
   parent_.onRequestCompleted();
 }
@@ -661,6 +668,8 @@ void InstanceImpl::PendingRequest::onFailure() {
         end_time - start_time_).count();
     latency_histogram_->recordValue(latency_us);
   }
+  // Complete per-shard per-command latency timer (auto-records on destruction)
+  command_latency_timer_.reset();
   pool_callbacks_.onFailure();
   parent_.refresh_manager_->onFailure(parent_.cluster_name_);
   parent_.onRequestCompleted();

source/extensions/filters/network/redis_proxy/conn_pool_impl.h

@@ -10,6 +10,7 @@
 #include "envoy/common/time.h"
 #include "envoy/extensions/filters/network/redis_proxy/v3/redis_proxy.pb.h"
 #include "envoy/stats/stats_macros.h"
+#include "envoy/stats/timespan.h"
 #include "envoy/thread_local/thread_local.h"
 #include "envoy/upstream/cluster_manager.h"
 
@@ -182,6 +183,7 @@ class InstanceImpl : public Instance, public std::enable_shared_from_this<Instan
     Stats::StatName command_;            // Command name for per-shard command stats
     Stats::Histogram* latency_histogram_{nullptr};  // Per-shard latency histogram
     MonotonicTime start_time_;           // Request start time for latency tracking
+    Stats::TimespanPtr command_latency_timer_;  // Per-shard per-command latency timer
   };
 
   struct ThreadLocalPool : public ThreadLocal::ThreadLocalObject,