added explanation for the magic 511 backlog number

[redis.git] / src / rio.h

diff --git a/src/rio.h b/src/rio.h
index 2a830eb575aacb751f5b24e29f4a5d1cafaddf09..8befe6676e78a3ff269073964eea050259d7fed5 100644 (file)
--- a/src/rio.h
+++ b/src/rio.h
@@ -2,6 +2,7 @@
 #define __REDIS_RIO_H
 
 #include <stdio.h>
+#include <stdint.h>
 #include "sds.h"
 
 struct _rio {
@@ -11,6 +12,14 @@ struct _rio {
     size_t (*read)(struct _rio *, void *buf, size_t len);
     size_t (*write)(struct _rio *, const void *buf, size_t len);
     off_t (*tell)(struct _rio *);
+    /* The update_cksum method if not NULL is used to compute the checksum of all the
+     * data that was read or written so far. The method should be designed so that
+     * can be called with the current checksum, and the buf and len fields pointing
+     * to the new block of data to add to the checksum computation. */
+    void (*update_cksum)(struct _rio *, const void *buf, size_t len);
+
+    /* The current checksum */
+    uint64_t cksum;
 
     /* Backend-specific vars. */
     union {
@@ -26,8 +35,26 @@ struct _rio {
 
 typedef struct _rio rio;
 
-#define rioWrite(rio,buf,len) ((rio)->write((rio),(buf),(len)))
-#define rioRead(rio,buf,len) ((rio)->read((rio),(buf),(len)))
+/* The following functions are our interface with the stream. They'll call the
+ * actual implementation of read / write / tell, and will update the checksum
+ * if needed. */
+
+static inline size_t rioWrite(rio *r, const void *buf, size_t len) {
+    if (r->update_cksum) r->update_cksum(r,buf,len);
+    return r->write(r,buf,len);
+}
+
+static inline size_t rioRead(rio *r, void *buf, size_t len) {
+    if (r->read(r,buf,len) == 1) {
+        if (r->update_cksum) r->update_cksum(r,buf,len);
+        return 1;
+    }
+    return 0;
+}
+
+static inline off_t rioTell(rio *r) {
+    return r->tell(r);
+}
 
 void rioInitWithFile(rio *r, FILE *fp);
 void rioInitWithBuffer(rio *r, sds s);
@@ -37,4 +64,6 @@ 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);
 
+void rioGenericUpdateChecksum(rio *r, const void *buf, size_t len);
+
 #endif