Add SonicDBConfig.getInstanceList() API (sonic-net#639)

#### Why I did it
SonicDBConfig.getInstanceList() API is missing in swsscommon.
The py-swsssdk library are going to be deprercated, to change all script to use swsscommon, we need add this missing API.


#### How I did it
Add SonicDBConfig.getInstanceList() API.

#### How to verify it
Pass all existed test case
Add new test case to cover new API.

#### Which release branch to backport (provide reason below if selected)

<!--
- Note we only backport fixes to a release branch, *not* features!
- Please also provide a reason for the backporting below.
- e.g.
- [x] 202006
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- [ ] 201811
- [ ] 201911
- [ ] 202006
- [ ] 202012
- [ ] 202106
- [ ] 202111
- [ ] 202205

#### Description for the changelog
Add SonicDBConfig.getInstanceList() API.

#### Link to config_db schema for YANG module changes

#### A picture of a cute animal (not mandatory but encouraged)


Co-authored-by: liuh-80 <azureuser@liuh-dev-vm-02.5fg3zjdzj2xezlx1yazx5oxkzd.hx.internal.cloudapp.net>
Co-authored-by: azureuser <[email protected]>

Author: 3 people

common/dbconnector.cpp

@@ -18,7 +18,7 @@ using namespace std;
 using namespace swss;
 
 void SonicDBConfig::parseDatabaseConfig(const string &file,
-                    std::unordered_map<std::string, RedisInstInfo> &inst_entry,
+                    std::map<std::string, RedisInstInfo> &inst_entry,
                     std::unordered_map<std::string, SonicDBInfo> &db_entry,
                     std::unordered_map<int, std::string> &separator_entry)
 {
@@ -72,7 +72,7 @@ void SonicDBConfig::initializeGlobalConfig(const string &file)
 {
     std::string local_file, dir_name, ns_name;
     std::unordered_map<std::string, SonicDBInfo> db_entry;
-    std::unordered_map<std::string, RedisInstInfo> inst_entry;
+    std::map<std::string, RedisInstInfo> inst_entry;
     std::unordered_map<int, std::string> separator_entry;
     std::lock_guard<std::recursive_mutex> guard(m_db_info_mutex);
 
@@ -164,7 +164,7 @@ void SonicDBConfig::initializeGlobalConfig(const string &file)
 void SonicDBConfig::initialize(const string &file)
 {
     std::unordered_map<std::string, SonicDBInfo> db_entry;
-    std::unordered_map<std::string, RedisInstInfo> inst_entry;
+    std::map<std::string, RedisInstInfo> inst_entry;
     std::unordered_map<int, std::string> separator_entry;
     std::lock_guard<std::recursive_mutex> guard(m_db_info_mutex);
 
@@ -201,7 +201,7 @@ void SonicDBConfig::validateNamespace(const string &netns)
         }
 
         // Check if the namespace is valid, check if this is a key in either of this map
-        unordered_map<string, unordered_map<string, RedisInstInfo>>::const_iterator entry = m_inst_info.find(netns);
+        unordered_map<string, map<string, RedisInstInfo>>::const_iterator entry = m_inst_info.find(netns);
         if (entry == m_inst_info.end())
         {
             SWSS_LOG_THROW("Namespace %s is not a valid namespace name in config file", netns.c_str());
@@ -391,10 +391,27 @@ std::vector<std::string> SonicDBConfig::getDbList(const std::string &netns)
     return dbNames;
 }
 
+map<string, RedisInstInfo> SonicDBConfig::getInstanceList(const std::string &netns)
+{
+    if (!m_init)
+    {
+        initialize();
+    }
+    validateNamespace(netns);
+
+    map<string, RedisInstInfo> result;
+    auto iterator = m_inst_info.find(netns);
+    if (iterator != m_inst_info.end()) {
+        return iterator->second;
+    }
+
+    return map<string, RedisInstInfo>();
+}
+
 constexpr const char *SonicDBConfig::DEFAULT_SONIC_DB_CONFIG_FILE;
 constexpr const char *SonicDBConfig::DEFAULT_SONIC_DB_GLOBAL_CONFIG_FILE;
 std::recursive_mutex SonicDBConfig::m_db_info_mutex;
-unordered_map<string, unordered_map<string, RedisInstInfo>> SonicDBConfig::m_inst_info;
+unordered_map<string, map<string, RedisInstInfo>> SonicDBConfig::m_inst_info;
 unordered_map<string, unordered_map<string, SonicDBInfo>> SonicDBConfig::m_db_info;
 unordered_map<string, unordered_map<int, string>> SonicDBConfig::m_db_separator;
 bool SonicDBConfig::m_init = false;

common/dbconnector.h

@@ -1,10 +1,11 @@
-#ifndef __DBCONNECTOR__
+    #ifndef __DBCONNECTOR__
 #define __DBCONNECTOR__
 
 #include <string>
 #include <vector>
 #include <unordered_map>
 #include <utility>
+#include <map>
 #include <memory>
 #include <mutex>
 
@@ -81,19 +82,20 @@ class SonicDBConfig
     static std::vector<std::string> getDbList(const std::string &netns = EMPTY_NAMESPACE);
     static bool isInit() { return m_init; };
     static bool isGlobalInit() { return m_global_init; };
+    static std::map<std::string, RedisInstInfo> getInstanceList(const std::string &netns = EMPTY_NAMESPACE);
 
 private:
     static std::recursive_mutex m_db_info_mutex;
     // { namespace { instName, { unix_socket_path, hostname, port } } }
-    static std::unordered_map<std::string, std::unordered_map<std::string, RedisInstInfo>> m_inst_info;
+    static std::unordered_map<std::string, std::map<std::string, RedisInstInfo>> m_inst_info;
     // { namespace, { dbName, {instName, dbId, separator} } }
     static std::unordered_map<std::string, std::unordered_map<std::string, SonicDBInfo>> m_db_info;
     // { namespace, { dbId, separator } }
     static std::unordered_map<std::string, std::unordered_map<int, std::string>> m_db_separator;
     static bool m_init;
     static bool m_global_init;
     static void parseDatabaseConfig(const std::string &file,
-                                    std::unordered_map<std::string, RedisInstInfo> &inst_entry,
+                                    std::map<std::string, RedisInstInfo> &inst_entry,
                                     std::unordered_map<std::string, SonicDBInfo> &db_entry,
                                     std::unordered_map<int, std::string> &separator_entry);
     static SonicDBInfo& getDbInfo(const std::string &dbName, const std::string &netns = EMPTY_NAMESPACE);

pyext/swsscommon.i

@@ -50,11 +50,13 @@
 
 %template(FieldValuePair) std::pair<std::string, std::string>;
 %template(FieldValuePairs) std::vector<std::pair<std::string, std::string>>;
+%template(FieldValuePairsList) std::vector<std::vector<std::pair<std::string, std::string>>>;
 %template(FieldValueMap) std::map<std::string, std::string>;
 %template(VectorString) std::vector<std::string>;
 %template(ScanResult) std::pair<int64_t, std::vector<std::string>>;
 %template(GetTableResult) std::map<std::string, std::map<std::string, std::string>>;
 %template(GetConfigResult) std::map<std::string, std::map<std::string, std::map<std::string, std::string>>>;
+%template(GetInstanceListResult) std::map<std::string, swss::RedisInstInfo>;
 
 %exception {
     try
@@ -82,15 +84,6 @@
     }
 }
 
-%template(FieldValuePair) std::pair<std::string, std::string>;
-%template(FieldValuePairs) std::vector<std::pair<std::string, std::string>>;
-%template(FieldValuePairsList) std::vector<std::vector<std::pair<std::string, std::string>>>;
-%template(FieldValueMap) std::map<std::string, std::string>;
-%template(VectorString) std::vector<std::string>;
-%template(ScanResult) std::pair<int64_t, std::vector<std::string>>;
-%template(GetTableResult) std::map<std::string, std::map<std::string, std::string>>;
-%template(GetConfigResult) std::map<std::string, std::map<std::string, std::map<std::string, std::string>>>;
-
 %typemap(out) std::shared_ptr<std::string> %{
     {
         auto& p = static_cast<std::shared_ptr<std::string>&>($1);

tests/redis_multi_ns_ut.cpp

@@ -1,10 +1,10 @@
 #include <iostream>
 #include <fstream>
+#include <map>
 #include "gtest/gtest.h"
 #include "common/dbconnector.h"
 #include "common/json.hpp"
 #include "common/table.h"
-#include <unordered_map>
 
 using namespace std;
 using namespace swss;
@@ -77,7 +77,7 @@ TEST(DBConnector, multi_ns_test)
             {
                 json j;
                 i >> j;
-                unordered_map<string, RedisInstInfo> m_inst_info;
+                map<string, RedisInstInfo> m_inst_info;
                 for (auto it = j["INSTANCES"].begin(); it!= j["INSTANCES"].end(); it++)
                 {
                    string instName = it.key();

tests/test_redis_ut.py

@@ -677,3 +677,13 @@ def test_DBConnectFailure():
     with pytest.raises(RuntimeError):
         db = swsscommon.DBConnector(0, nonexisting_host, 0)
 
+def test_SonicDBConfigGetInstanceList():
+    """ Verify that SonicDBConfig.getInstanceList will return correct redis instance information """
+
+    instanceList = swsscommon.SonicDBConfig.getInstanceList()
+    keys = instanceList.keys()
+
+    assert keys[0] == 'redis'
+    assert instanceList['redis'].unixSocketPath == '/var/run/redis/redis.sock'
+    assert instanceList['redis'].hostname == '127.0.0.1'
+    assert instanceList['redis'].port == 6379