Redis: Add new backend

src/storage/backend/redis/Redis.h

@@ -0,0 +1,91 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#pragma once
+
+#include "zeek/iosource/IOSource.h"
+#include "zeek/storage/Backend.h"
+
+// Forward declare some types from hiredis to avoid including the header
+struct redisContext;
+struct redisAsyncContext;
+struct redisReply;
+
+namespace zeek::storage::backend::redis {
+
+class Redis : public Backend, public iosource::IOSource {
+public:
+    Redis(std::string_view tag) : Backend(true, tag), IOSource(true) {}
+    ~Redis() override = default;
+
+    static BackendPtr Instantiate(std::string_view tag);
+
+    /**
+     * Returns a descriptive tag representing the source for debugging.
+     * This has to be overloaded for Redis because IOSource requires it.
+     *
+     * @return The debugging name.
+     */
+    const char* Tag() override { return tag.c_str(); }
+
+    /**
+     * Called by the manager system to open the backend.
+     */
+    ErrorResult DoOpen(RecordValPtr options) override;
+
+    /**
+     * Finalizes the backend when it's being closed.
+     */
+    void Close() override;
+
+    /**
+     * Returns whether the backend is opened.
+     */
+    bool IsOpen() override { return connected; }
+
+    /**
+     * The workhorse method for Retrieve().
+     */
+    ErrorResult DoPut(ValPtr key, ValPtr value, bool overwrite = true, double expiration_time = 0,
+                      ErrorResultCallback* cb = nullptr) override;
+
+    /**
+     * The workhorse method for Get().
+     */
+    ValResult DoGet(ValPtr key, ValResultCallback* cb = nullptr) override;
+
+    /**
+     * The workhorse method for Erase().
+     */
+    ErrorResult DoErase(ValPtr key, ErrorResultCallback* cb = nullptr) override;
+
+    // IOSource interface
+    double GetNextTimeout() override { return -1; }
+    void Process() override {}
+    void ProcessFd(int fd, int flags) override;
+
+    // Hiredis async interface
+    void OnConnect(int status);
+    void OnDisconnect(int status);
+
+    void OnAddRead();
+    void OnDelRead();
+    void OnAddWrite();
+    void OnDelWrite();
+
+    void HandlePutResult(redisReply* reply, ErrorResultCallback* callback);
+    void HandleGetResult(redisReply* reply, ValResultCallback* callback);
+    void HandleEraseResult(redisReply* reply, ErrorResultCallback* callback);
+
+private:
+    ValResult ParseGetReply(redisReply* reply) const;
+
+    redisContext* ctx = nullptr;
+    redisAsyncContext* async_ctx = nullptr;
+    bool connected = true;
+
+    std::string server_addr;
+    std::string key_prefix;
+    bool async_mode = false;
+};
+
+} // namespace zeek::storage::backend::redis