stream_handler.h

#ifndef _STREAM_HANDLER_H
#define _STREAM_HANDLER_H
/*
 * Fledge storage service.
 *
 * Copyright (c) 2019 Dianomic Systems Inc.
 *
 * Released under the Apache 2.0 Licence
 *
 * Author: Mark Riddoch
 */
#include <thread>
#include <mutex>
#include <condition_variable>
#include <vector>
#include <map>
#include <sys/epoll.h>
#include <reading_stream.h>

#define MAX_EVENTS    40    // Number of epoll events in one epoll_wait call
#define RDS_BLOCK    10000  // Number of readings to insert in each call to the storage plugin
#define BLOCK_POOL_SIZES 512    // Increments of block sizes in a block pool

class StorageApi;

class StreamHandler {
    public:
        StreamHandler(StorageApi *);
        ~StreamHandler();
        void            handler();
        uint32_t        createStream(uint32_t *token);
    private:
        class Stream {
            public:
                Stream();
                ~Stream();
                uint32_t    create(int epollfd, uint32_t *token);
                void        handleEvent(int epollfd, StorageApi *api, uint32_t events);
            private:
                class MemoryPool {
                        public:
                            MemoryPool(size_t blkIncr) : m_blkIncr(blkIncr) {};
                            ~MemoryPool();
                            void        *allocate(size_t size);
                            void        release(void *handle);
                        private:
                            size_t      rndSize(size_t size)
                                    { 
                                        return m_blkIncr * ((size + m_blkIncr - 1)
                                                    / m_blkIncr);
                                    };
                            void        createPool(size_t size);
                            void        growPool(std::vector<void *>*, size_t);
                            size_t      m_blkIncr;
                            std::map<size_t, std::vector<void *>* >
                                    m_pool;
                    };
                    void        setNonBlocking(int fd);
                    unsigned int    available(int fd);
                    void        queueInsert(StorageApi *api, unsigned int nReadings, bool commit);
                    void        dump(int n);
                    enum { Closed, Listen, AwaitingToken, Connected }
                                m_status;
                    int     m_socket;
                    uint16_t    m_port;
                    uint32_t    m_token;
                    uint32_t    m_blockNo;
                    enum { BlkHdr, RdHdr, RdBody }
                                m_protocolState;
                    uint32_t    m_readingNo;
                    uint32_t    m_blockSize;
                    size_t      m_readingSize;
                    struct epoll_event
                            m_event;
                    ReadingStream   *m_readings[RDS_BLOCK+1];
                    ReadingStream   *m_currentReading;
                    MemoryPool  *m_blockPool;
                    std::string m_lastAsset;
                    bool        m_sameAsset;
        };
        StorageApi      *m_api;
        std::thread     m_handlerThread;
        int         m_tokens;
        std::condition_variable m_streamsCV;
        std::mutex      m_streamsMutex;
        std::vector<Stream *>   m_streams;
        bool            m_running;
        int         m_pollfd;
};
#endif