[eventd] Fix eventd UT flakiness (sonic-net#17055)

### Why I did it

Fix flakiness of eventd UT - run sub after capture service starts

##### Work item tracking
- Microsoft ADO **(number only)**:25650744

#### How I did it

Run sub socket after capture socket is initialized

#### How to verify it

Pipeline

src/sonic-eventd/Makefile

@@ -29,7 +29,7 @@ endif
 -include rsyslog_plugin/subdir.mk
 -include rsyslog_plugin_tests/subdir.mk
 
-all: sonic-eventd eventd-tool rsyslog-plugin
+all: sonic-eventd eventd-tests eventd-tool rsyslog-plugin rsyslog-plugin-tests
 
 sonic-eventd: $(OBJS)
 	@echo 'Building target: $@'

src/sonic-eventd/src/eventd.cpp

@@ -546,9 +546,9 @@ capture_service::set_control(capture_control_t ctrl, event_serialized_lst_t *lst
     switch(ctrl) {
         case INIT_CAPTURE:
             m_thr = thread(&capture_service::do_capture, this);
-            for(int i=0; !m_cap_run && (i < 100); ++i) {
+            for(int i=0; !m_cap_run && (i < CAPTURE_SERVICE_POLLING_RETRIES); ++i) {
                 /* Wait max a second for thread to init */
-                this_thread::sleep_for(chrono::milliseconds(10));
+                this_thread::sleep_for(chrono::milliseconds(CAPTURE_SERVICE_POLLING_DURATION));
             }
             RET_ON_ERR(m_cap_run, "Failed to init capture");
             m_ctrl = ctrl;

src/sonic-eventd/src/eventd.h

@@ -21,6 +21,8 @@ typedef enum {
 
 #define EVENTS_STATS_FIELD_NAME "value"
 #define STATS_HEARTBEAT_MIN 300
+#define CAPTURE_SERVICE_POLLING_DURATION 10
+#define CAPTURE_SERVICE_POLLING_RETRIES 100
 
 /*
  *  Started by eventd_service.

src/sonic-eventd/tests/eventd_ut.cpp

@@ -152,25 +152,23 @@ static const test_data_t ldata[] = {
 
 
 void run_cap(void *zctx, bool &term, string &read_source,
-        int &cnt)
+        int &cnt, bool &should_read_control)
 {
     void *mock_cap = zmq_socket (zctx, ZMQ_SUB);
     string source;
     internal_event_t ev_int;
     int block_ms = 200;
     int i=0;
-    static int proxy_finished_init = false;
 
     EXPECT_TRUE(NULL != mock_cap);
     EXPECT_EQ(0, zmq_connect(mock_cap, get_config(CAPTURE_END_KEY).c_str()));
     EXPECT_EQ(0, zmq_setsockopt(mock_cap, ZMQ_SUBSCRIBE, "", 0));
     EXPECT_EQ(0, zmq_setsockopt(mock_cap, ZMQ_RCVTIMEO, &block_ms, sizeof (block_ms)));
 
-    if(!proxy_finished_init) {
+    if(should_read_control) {
         zmq_msg_t msg;
         zmq_msg_init(&msg);
-        EXPECT_EQ(1, zmq_msg_recv(&msg, mock_cap, 0)); // Subscription message
-        proxy_finished_init = true;
+        EXPECT_NE(1, zmq_msg_recv(&msg, mock_cap, 0)); // Subscription message should be read by do_capture
     }
 
     while(!term) {
@@ -227,10 +225,10 @@ void run_pub(void *mock_pub, const string wr_source, internal_events_lst_t &lst)
     }
 }
 
-
 TEST(eventd, proxy)
 {
     printf("Proxy TEST started\n");
+    bool should_read_control = false;
     bool term_sub = false;
     bool term_cap = false;
     string rd_csource, rd_source, wr_source("hello");
@@ -247,12 +245,12 @@ TEST(eventd, proxy)
     /* Starting proxy */
     EXPECT_EQ(0, pxy->init());
 
+    /* capture in a thread */
+    thread thrc(&run_cap, zctx, ref(term_cap), ref(rd_csource), ref(rd_cevts_sz), ref(should_read_control));
+
     /* subscriber in a thread */
     thread thr(&run_sub, zctx, ref(term_sub), ref(rd_source), ref(rd_evts), ref(rd_evts_sz));
 
-    /* capture in a thread */
-    thread thrc(&run_cap, zctx, ref(term_cap), ref(rd_csource), ref(rd_cevts_sz));
-
     /* Init pub connection */
     void *mock_pub = init_pub(zctx);
 
@@ -275,9 +273,6 @@ TEST(eventd, proxy)
     }
     this_thread::sleep_for(chrono::milliseconds(1000));
 
-    delete pxy;
-    pxy = NULL;
-
     term_sub = true;
     term_cap = true;
 
@@ -287,6 +282,18 @@ TEST(eventd, proxy)
     EXPECT_EQ(rd_cevts_sz,  wr_evts.size());
 
     zmq_close(mock_pub);
+
+    /* Do control test */
+
+    should_read_control = true;
+
+    /* capture in a thread */
+    thread thrcc(&run_cap, zctx, ref(term_cap), ref(rd_csource), ref(rd_cevts_sz), ref(should_read_control));
+
+    delete pxy;
+    pxy = NULL;
+
+    thrcc.join();
     zmq_ctx_term(zctx);
 
     /* Provide time for async proxy removal to complete */
@@ -295,7 +302,6 @@ TEST(eventd, proxy)
     printf("eventd_proxy is tested GOOD\n");
 }
 
-
 TEST(eventd, capture)
 {
     printf("Capture TEST started\n");
@@ -329,9 +335,6 @@ TEST(eventd, capture)
     /* Starting proxy */
     EXPECT_EQ(0, pxy->init());
 
-    /* Run subscriber; Else publisher will drop events on floor, with no subscriber. */
-    thread thr_sub(&run_sub, zctx, ref(term_sub), ref(sub_source), ref(sub_evts), ref(sub_evts_sz));
-
     /* Create capture service */
     capture_service *pcap = new capture_service(zctx, cache_max, &stats_instance);
 
@@ -341,6 +344,9 @@ TEST(eventd, capture)
     /* Initialize the capture */
     EXPECT_EQ(0, pcap->set_control(INIT_CAPTURE));
 
+    /* Run subscriber; Else publisher will drop events on floor, with no subscriber. */
+    thread thr_sub(&run_sub, zctx, ref(term_sub), ref(sub_source), ref(sub_evts), ref(sub_evts_sz));
+
     EXPECT_TRUE(init_cache > 1);
     EXPECT_TRUE((cache_max+3) < (int)ARRAY_SIZE(ldata));
 
@@ -473,9 +479,6 @@ TEST(eventd, captureCacheMax)
     /* Starting proxy */
     EXPECT_EQ(0, pxy->init());
 
-    /* Run subscriber; Else publisher will drop events on floor, with no subscriber. */
-    thread thr_sub(&run_sub, zctx, ref(term_sub), ref(sub_source), ref(sub_evts), ref(sub_evts_sz));
-
     /* Create capture service */
     capture_service *pcap = new capture_service(zctx, cache_max, &stats_instance);
 
@@ -484,6 +487,9 @@ TEST(eventd, captureCacheMax)
 
     EXPECT_TRUE(init_cache > 1);
 
+    /* Run subscriber; Else publisher will drop events on floor, with no subscriber. */
+    thread thr_sub(&run_sub, zctx, ref(term_sub), ref(sub_source), ref(sub_evts), ref(sub_evts_sz));
+
     /* Collect few serailized strings of events for startup cache */
     for(int i=0; i < init_cache; ++i) {
         internal_event_t ev(create_ev(ldata[i]));
@@ -595,6 +601,7 @@ TEST(eventd, service)
     }
 
     thread thread_service(&run_eventd_service);
+    this_thread::sleep_for(chrono::milliseconds(CAPTURE_SERVICE_POLLING_DURATION * CAPTURE_SERVICE_POLLING_RETRIES));
 
     /* Need client side service to interact with server side */
     EXPECT_EQ(0, service.init_client(zctx));
@@ -610,7 +617,7 @@ TEST(eventd, service)
         string wr_source("hello");
 
         /* Test service startup caching */
-        event_serialized_lst_t evts_start, evts_read;
+        event_serialized_lst_t evts_start, evts_read, polled_events;
 
         for(int i=0; i<wr_sz; ++i) {
             string evt_str;
@@ -624,15 +631,32 @@ TEST(eventd, service)
         /* Publish events. */
         run_pub(mock_pub, wr_source, wr_evts);
 
-        /* Published events must have been captured. Give a pause, to ensure sent. */
-        this_thread::sleep_for(chrono::milliseconds(200));
+        int max_polling_duration = 2000;
+        int polling_interval = 100;
+        auto poll_start_ts = chrono::steady_clock::now();
+
+        while(true) {
+            auto current_ts = chrono::steady_clock::now();
+            if(chrono::duration_cast<chrono::milliseconds>(current_ts - poll_start_ts).count() >= max_polling_duration) {
+                break;
+            }
+            event_serialized_lst_t read_events;
+            service.cache_read(read_events);
+            polled_events.insert(polled_events.end(), read_events.begin(), read_events.end());
+            if (!read_events.empty()) {
+                break;
+            }
+            this_thread::sleep_for(chrono::milliseconds(polling_interval));	    
+        }
 
         EXPECT_EQ(0, service.cache_stop());
 
-        /* Read the cache; expect wr_sz events */
+        /* Read remaining events in cache, if any */
         EXPECT_EQ(0, service.cache_read(evts_read));
 
-        EXPECT_EQ(evts_read, evts_start);
+        polled_events.insert(polled_events.end(), evts_read.begin(), evts_read.end());
+
+        EXPECT_EQ(polled_events, evts_start);
 
         zmq_close(mock_pub);
     }

src/sonic-eventd/tests/main.cpp

@@ -1,6 +1,7 @@
 #include "gtest/gtest.h"
 #include "dbconnector.h"
 #include <iostream>
+#include <stdexcept>
 
 using namespace std;
 using namespace swss;
@@ -20,57 +21,34 @@ class SwsscommonEnvironment : public ::testing::Environment {
     // Override this to define how to set up the environment
     void SetUp() override {
         // by default , init should be false
-        cout<<"Default : isInit = "<<SonicDBConfig::isInit()<<endl;
+        cout << "Default : isInit = " << SonicDBConfig::isInit() << endl;
         EXPECT_FALSE(SonicDBConfig::isInit());
 
-        // load nonexisting file, should throw exception with NO file existing
-        try
-        {
-            cout<<"INIT: loading nonexisting db config file"<<endl;
-            SonicDBConfig::initialize(nonexisting_file);
-        }
-        catch (exception &e)
-        {
-            EXPECT_TRUE(strstr(e.what(), "Sonic database config file doesn't exist"));
-        }
+        EXPECT_THROW(SonicDBConfig::initialize(nonexisting_file), runtime_error);
+
         EXPECT_FALSE(SonicDBConfig::isInit());
 
         // load local config file, init should be true
         SonicDBConfig::initialize(existing_file);
-        cout<<"INIT: load local db config file, isInit = "<<SonicDBConfig::isInit()<<endl;
+        cout << "INIT: load local db config file, isInit = " << SonicDBConfig::isInit() << endl;
         EXPECT_TRUE(SonicDBConfig::isInit());
 
         // Test the database_global.json file
         // by default , global_init should be false
-        cout<<"Default : isGlobalInit = "<<SonicDBConfig::isGlobalInit()<<endl;
+        cout << "Default : isGlobalInit = " << SonicDBConfig::isGlobalInit() << endl;
         EXPECT_FALSE(SonicDBConfig::isGlobalInit());
 
         // Call an API which actually needs the data populated by SonicDBConfig::initializeGlobalConfig
-        try
-        {
-            cout<<"INIT: Invoking SonicDBConfig::getDbId(APPL_DB, asic0)"<<endl;
-            SonicDBConfig::getDbId(TEST_DB, TEST_NAMESPACE);
-        }
-        catch (exception &e)
-        {
-            EXPECT_TRUE(strstr(e.what(), "Initialize global DB config using API SonicDBConfig::initializeGlobalConfig"));
-        }
+        EXPECT_THROW(SonicDBConfig::getDbId(TEST_DB, TEST_NAMESPACE), runtime_error);
 
         // load local global file, init should be true
         SonicDBConfig::initializeGlobalConfig(global_existing_file);
-        cout<<"INIT: load global db config file, isInit = "<<SonicDBConfig::isGlobalInit()<<endl;
+        cout << "INIT: load global db config file, isInit = " << SonicDBConfig::isGlobalInit() << endl;
         EXPECT_TRUE(SonicDBConfig::isGlobalInit());
 
         // Call an API with wrong namespace passed
-        try
-        {
-            cout<<"INIT: Invoking SonicDBConfig::getDbId(APPL_DB, invalid)"<<endl;
-            SonicDBConfig::getDbId(TEST_DB, INVALID_NAMESPACE);
-        }
-        catch (exception &e)
-        {
-            EXPECT_TRUE(strstr(e.what(), "Namespace invalid is not a valid namespace name in config file"));
-        }
+        cout << "INIT: Invoking SonicDBConfig::getDbId(APPL_DB, invalid)" << endl;
+        EXPECT_THROW(SonicDBConfig::getDbId(TEST_DB, INVALID_NAMESPACE), out_of_range);
 
         // Get this info handy
         try