Redis rio的代碼很少，基本上包了一個虛基類:

struct _rio {
? ? void (*update_cksum)(struct _rio *, const void *buf, size_t len);

? ? /* The current checksum */
? ? uint64_t cksum;

? ? /* Backend-specific vars. */
? ? union {
? ? ? ? struct {
? ? ? ? ? ? sds ptr;
? ? ? ? ? ? off_t pos;
? ? ? ? } buffer;
? ? ? ? struct {
? ? ? ? ? ? FILE *fp;
? ? ? ? ? ? off_t buffered; /* Bytes written since last fsync. */
? ? ? ? ? ? off_t autosync; ? // buffered超過這個值自動更新，默認(rèn)為0
? ? ? ? } file;
? ? } io;
};

API如下:

static inline size_t rioWrite(rio *r, const void *buf, size_t len) ; ?// 調(diào)用 rio->write,同時更新checksum
static inline size_t rioRead(rio *r, void *buf, size_t len) // 調(diào)用 rio->read,同時更新checksum
static inline off_t rioTell(rio *r); ?//直接調(diào)用rio->tell

void rioInitWithFile(rio *r, FILE *fp); ?// 初始化rio->io->file
void rioInitWithBuffer(rio *r, sds s); ?// 初始化rio->io->buffer

// ?以下幾個是High Level Interface,用于寫AOF文件
size_t rioWriteBulkCount(rio *r, char prefix, int count);
size_t rioWriteBulkString(rio *r, const char *buf, size_t len);
size_t rioWriteBulkLongLong(rio *r, long long l);
size_t rioWriteBulkDouble(rio *r, double d);

// 更新crc64 checksum

void rioGenericUpdateChecksum(rio *r, const void *buf, size_t len);

// 設(shè)置自動sync的字節(jié)數(shù)

void rioSetAutoSync(rio *r, off_t bytes);

?

Redis rio