Throw proper exceptions when talking with Redis (#384)

* Add new exception RedisResponseError * Rename to RedisError * Throw bad_alloc when ouf of memory * Handle and throw exception in RedisPipeline
sonic-net · Sep 18, 2020 · 5776ef5 · 5776ef5
1 parent 2b9a00f
commit 5776ef5
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Showing 3 changed files with 62 additions and 6 deletions.
diff --git a/common/redispipeline.h b/common/redispipeline.h
@@ -33,7 +33,13 @@ class RedisPipeline {
             case REDIS_REPLY_STATUS:
             case REDIS_REPLY_INTEGER:
             {
-                redisAppendFormattedCommand(m_db->getContext(), command.c_str(), command.length());
+                int rc = redisAppendFormattedCommand(m_db->getContext(), command.c_str(), command.length());
+                if (rc != REDIS_OK)
+                {
+                    // The only reason of error is REDIS_ERR_OOM (Out of memory)
+                    // ref: https://github.com/redis/hiredis/blob/master/hiredis.c
+                    throw std::bad_alloc();
+                }
                 m_expectedTypes.push(expectedType);
                 m_remaining++;
                 mayflush();
@@ -71,7 +77,11 @@ class RedisPipeline {
         if (m_remaining == 0) return NULL;
 
         redisReply *reply;
-        redisGetReply(m_db->getContext(), (void**)&reply);
+        int rc = redisGetReply(m_db->getContext(), (void**)&reply);
+        if (rc != REDIS_OK)
+        {
+            throw RedisError("Failed to redisGetReply in RedisPipeline::pop", m_db->getContext());
+        }
         RedisReply r(reply);
         m_remaining--;
 

diff --git a/common/redisreply.cpp b/common/redisreply.cpp
@@ -30,15 +30,37 @@ inline void guard(FUNC func, const char* command)
 
 RedisReply::RedisReply(DBConnector *db, const RedisCommand& command)
 {
-    redisAppendFormattedCommand(db->getContext(), command.c_str(), command.length());
-    redisGetReply(db->getContext(), (void**)&m_reply);
+    int rc = redisAppendFormattedCommand(db->getContext(), command.c_str(), command.length());
+    if (rc != REDIS_OK)
+    {
+        // The only reason of error is REDIS_ERR_OOM (Out of memory)
+        // ref: https://github.com/redis/hiredis/blob/master/hiredis.c
+        throw bad_alloc();
+    }
+
+    rc = redisGetReply(db->getContext(), (void**)&m_reply);
+    if (rc != REDIS_OK)
+    {
+        throw RedisError("Failed to redisGetReply with " + string(command.c_str()), db->getContext());
+    }
     guard([&]{checkReply();}, command.c_str());
 }
 
 RedisReply::RedisReply(DBConnector *db, const string &command)
 {
-    redisAppendCommand(db->getContext(), command.c_str());
-    redisGetReply(db->getContext(), (void**)&m_reply);
+    int rc = redisAppendCommand(db->getContext(), command.c_str());
+    if (rc != REDIS_OK)
+    {
+        // The only reason of error is REDIS_ERR_OOM (Out of memory)
+        // ref: https://github.com/redis/hiredis/blob/master/hiredis.c
+        throw bad_alloc();
+    }
+
+    rc = redisGetReply(db->getContext(), (void**)&m_reply);
+    if (rc != REDIS_OK)
+    {
+        throw RedisError("Failed to redisGetReply with " + command, db->getContext());
+    }
     guard([&]{checkReply();}, command.c_str());
 }
 

diff --git a/common/redisreply.h b/common/redisreply.h
@@ -2,13 +2,37 @@
 #define __REDISREPLY__
 
 #include <hiredis/hiredis.h>
+#include <string>
 #include <stdexcept>
 #include "rediscommand.h"
 
 namespace swss {
 
 class DBConnector;
 
+class RedisError : public std::runtime_error
+{
+    int m_err;
+    std::string m_errstr;
+    mutable std::string m_message;
+public:
+    RedisError(const std::string& arg, redisContext *ctx)
+        : std::runtime_error(arg)
+        , m_err(ctx->err)
+        , m_errstr(ctx->errstr)
+    {
+    }
+
+    const char *what() const noexcept override
+    {
+        if (m_message.empty())
+        {
+            m_message = std::string("RedisResponseError: ") + std::runtime_error::what() + ", err=" + std::to_string(m_err) + ": errstr=" + m_errstr;
+        }
+        return m_message.c_str();
+    }
+};
+
 class RedisReply
 {
 public: