This fix provides a max_queue_length attribute for the sandesh

queues on the send and recieve end
A new sandesh field has been added to the following UVE to
provide this information:
SandeshModuleClientTrace (reports send sandesh sm max_queu_size)
SandeshMessageStatsReq (reports send sandesh queue max_queue_size)
ShowCollectorServerResp (reports collector sandesh SM max_queue_size)

Currently the work_queue implementation already has a variable
max_queue_len_ in C++, but python does not have it. This variable
maintains the max_q_size reached so far. This is added as part of the
fix.
Partial-Bug: 1576798
Change-Id: Ifdde919aa9ad8c2b4f2600f8673af62123875fc2

src/analytics/collector.cc

@@ -480,6 +480,7 @@ void Collector::GetGeneratorSummaryInfo(vector<GeneratorSummaryInfo> *genlist) {
                     gsinfo.set_db_drop_level(db_drop_level);
                 }
             }
+            gsinfo.set_max_sm_queue_count(gen->GetSandeshStateMachineMaxQueueCount());
             genlist->push_back(gsinfo);
         }
     }

src/analytics/collector_uve.sandesh

@@ -112,6 +112,7 @@ struct GeneratorSummaryInfo {
     7: optional u64                        db_queue_count
     8: optional string                     db_drop_level
     9: optional bool                       sm_back_pressure
+    10: optional u64                       max_sm_queue_count
 }
 
 /**

src/analytics/generator.h

@@ -91,6 +91,9 @@ class SandeshGenerator : public Generator {
     void StartDbifReinit();
     virtual DbHandler * GetDbHandler() const { return db_handler_.get(); }
     bool UseGlobalDbHandler() const { return use_global_dbhandler_; }
+    uint32_t GetSandeshStateMachineMaxQueueCount() const {
+        return state_machine_->GetMaxQueueCount();
+    }
 
 private:
     virtual bool ProcessRules(const VizMsg *vmsg, bool rsc);

src/base/queue_task.h

@@ -564,6 +564,7 @@ class WorkQueue {
         }
         AtomicDecrementQueueCount(&entry);
         drops_++;
+        max_queue_len_ = count_;
         return false;
     }
 

src/base/test/queue_task_test.cc

@@ -208,7 +208,7 @@ class QueueTaskTest : public ::testing::Test {
     tbb::atomic<bool> shutdown_test_exit_callback_sleep_;
 };
 
-TEST_F(QueueTaskTest, StartRunnerBasic) {
+TEST_F(QueueTaskTest, StartRunnerBasic)
     TaskScheduler *scheduler = TaskScheduler::GetInstance();
     // Always do start runner
     work_queue_.SetStartRunnerFunc(
@@ -244,6 +244,24 @@ TEST_F(QueueTaskTest, StartRunnerBasic) {
     EXPECT_EQ(2, work_queue_.NumEnqueues());
     EXPECT_EQ(1, work_queue_.NumDequeues());
     EXPECT_EQ(1, work_queue_.Length());
+    // Verify WorkQueue max_queue_len_
+    EXPECT_EQ(1, work_queue_.max_queue_len());
+    work_queue_.Enqueue(enqueue_counter++);
+    work_queue_.Enqueue(enqueue_counter++);
+    work_queue_.Enqueue(enqueue_counter++);
+    task_util::WaitForIdle(1);
+    EXPECT_EQ(3, work_queue_.max_queue_len());
+    // Add test case for bounded workq
+    work_queue_.SetBounded(true);
+    work_queue_.size_(4);
+    work_queue_.Enqueue(enqueue_counter++);
+    work_queue_.Enqueue(enqueue_counter++);
+    work_queue_.Enqueue(enqueue_counter++);
+    work_queue_.Enqueue(enqueue_counter++);
+    EXPECT_EQ(4, work_queue_.max_queue_len());
+    work_queue_.Enqueue(enqueue_counter++);
+    EXPECT_EQ(4, work_queue_.max_queue_len());
+    task_util::WaitForIdle(1);
 }
 
 TEST_F(QueueTaskTest, StartRunnerInternals) {