Phase 24.2: Database Layer & State Management

src/cache/redis_client.h

@@ -0,0 +1,284 @@
+/**
+ * @file redis_client.h
+ * @brief Redis caching and pub/sub client for RootStream
+ * 
+ * Provides key-value operations, hash operations, list operations,
+ * and pub/sub functionality for real-time state synchronization.
+ */
+
+#ifndef ROOTSTREAM_REDIS_CLIENT_H
+#define ROOTSTREAM_REDIS_CLIENT_H
+
+#include <string>
+#include <map>
+#include <vector>
+#include <functional>
+#include <memory>
+#include <mutex>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// C-compatible opaque handle
+typedef struct RedisClient RedisClient;
+
+/**
+ * Initialize Redis client
+ * @param client Output pointer for client handle
+ * @param host Redis server host
+ * @param port Redis server port
+ * @return 0 on success, negative on error
+ */
+int redis_client_init(RedisClient** client, const char* host, uint16_t port);
+
+/**
+ * Set a key-value pair
+ * @param client Redis client handle
+ * @param key Key to set
+ * @param value Value to set
+ * @param ttl_seconds TTL in seconds (0 for no expiration)
+ * @return 0 on success, negative on error
+ */
+int redis_client_set(RedisClient* client, const char* key, const char* value, uint32_t ttl_seconds);
+
+/**
+ * Get a value by key
+ * @param client Redis client handle
+ * @param key Key to get
+ * @param value Output buffer (caller must free)
+ * @return 0 on success, negative on error
+ */
+int redis_client_get(RedisClient* client, const char* key, char** value);
+
+/**
+ * Delete a key
+ * @param client Redis client handle
+ * @param key Key to delete
+ * @return 0 on success, negative on error
+ */
+int redis_client_del(RedisClient* client, const char* key);
+
+/**
+ * Check if database connection is healthy
+ * @param client Redis client handle
+ * @return 1 if connected, 0 if not
+ */
+int redis_client_is_connected(RedisClient* client);
+
+/**
+ * Cleanup and destroy Redis client
+ * @param client Redis client to cleanup
+ */
+void redis_client_cleanup(RedisClient* client);
+
+#ifdef __cplusplus
+}
+#endif
+
+// C++ interface
+#ifdef __cplusplus
+
+#include <hiredis/hiredis.h>
+
+namespace rootstream {
+namespace cache {
+
+/**
+ * Redis client for caching and pub/sub
+ */
+class RedisClient {
+public:
+    RedisClient();
+    ~RedisClient();
+
+    /**
+     * Initialize connection to Redis server
+     * @param host Redis server host
+     * @param port Redis server port (default 6379)
+     * @return 0 on success, negative on error
+     */
+    int init(const std::string& host, uint16_t port = 6379);
+
+    // ========================================================================
+    // Key-Value Operations
+    // ========================================================================
+
+    /**
+     * Set a key-value pair
+     * @param key Key to set
+     * @param value Value to set
+     * @param ttl_seconds TTL in seconds (0 for no expiration)
+     * @return 0 on success, negative on error
+     */
+    int set(const std::string& key, const std::string& value, uint32_t ttl_seconds = 0);
+
+    /**
+     * Get value by key
+     * @param key Key to retrieve
+     * @param value Output parameter for value
+     * @return 0 on success, negative on error (key not found)
+     */
+    int get(const std::string& key, std::string& value);
+
+    /**
+     * Delete a key
+     * @param key Key to delete
+     * @return 0 on success, negative on error
+     */
+    int del(const std::string& key);
+
+    /**
+     * Check if key exists
+     * @param key Key to check
+     * @return 1 if exists, 0 if not, negative on error
+     */
+    int exists(const std::string& key);
+
+    // ========================================================================
+    // Hash Operations
+    // ========================================================================
+
+    /**
+     * Set a field in a hash
+     * @param key Hash key
+     * @param field Field name
+     * @param value Field value
+     * @return 0 on success, negative on error
+     */
+    int hset(const std::string& key, const std::string& field, const std::string& value);
+
+    /**
+     * Get a field from a hash
+     * @param key Hash key
+     * @param field Field name
+     * @param value Output parameter for field value
+     * @return 0 on success, negative on error
+     */
+    int hget(const std::string& key, const std::string& field, std::string& value);
+
+    /**
+     * Delete a field from a hash
+     * @param key Hash key
+     * @param field Field name
+     * @return 0 on success, negative on error
+     */
+    int hdel(const std::string& key, const std::string& field);
+
+    /**
+     * Get all fields and values from a hash
+     * @param key Hash key
+     * @param data Output map of field -> value
+     * @return 0 on success, negative on error
+     */
+    int hgetall(const std::string& key, std::map<std::string, std::string>& data);
+
+    // ========================================================================
+    // List Operations
+    // ========================================================================
+
+    /**
+     * Push value to left side of list
+     * @param key List key
+     * @param value Value to push
+     * @return 0 on success, negative on error
+     */
+    int lpush(const std::string& key, const std::string& value);
+
+    /**
+     * Pop value from right side of list
+     * @param key List key
+     * @param value Output parameter for popped value
+     * @return 0 on success, negative on error
+     */
+    int rpop(const std::string& key, std::string& value);
+
+    /**
+     * Get length of list
+     * @param key List key
+     * @return List length, or negative on error
+     */
+    int llen(const std::string& key);
+
+    // ========================================================================
+    // Pub/Sub Operations
+    // ========================================================================
+
+    /**
+     * Publish a message to a channel
+     * @param channel Channel name
+     * @param message Message to publish
+     * @return 0 on success, negative on error
+     */
+    int publish(const std::string& channel, const std::string& message);
+
+    // ========================================================================
+    // Transaction Operations
+    // ========================================================================
+
+    /**
+     * Begin a transaction
+     * @return 0 on success, negative on error
+     */
+    int multi();
+
+    /**
+     * Execute queued commands
+     * @return 0 on success, negative on error
+     */
+    int exec();
+
+    /**
+     * Discard queued commands
+     * @return 0 on success, negative on error
+     */
+    int discard();
+
+    // ========================================================================
+    // TTL Management
+    // ========================================================================
+
+    /**
+     * Set expiration time on a key
+     * @param key Key to expire
+     * @param seconds TTL in seconds
+     * @return 0 on success, negative on error
+     */
+    int expire(const std::string& key, uint32_t seconds);
+
+    /**
+     * Get TTL of a key
+     * @param key Key to check
+     * @return TTL in seconds, -1 if no expiration, -2 if key doesn't exist
+     */
+    int ttl(const std::string& key);
+
+    /**
+     * Check if connected to Redis
+     * @return true if connected
+     */
+    bool isConnected() const;
+
+    /**
+     * Cleanup resources
+     */
+    void cleanup();
+
+private:
+    redisContext* context_;
+    std::string host_;
+    uint16_t port_;
+    bool initialized_;
+    std::mutex mutex_;
+
+    // Helper to execute command
+    redisReply* executeCommand(const char* format, ...);
+    void freeReply(redisReply* reply);
+};
+
+} // namespace cache
+} // namespace rootstream
+
+#endif // __cplusplus
+
+#endif // ROOTSTREAM_REDIS_CLIENT_H