Expose API for streaming bytes to a reply

hiredis.c

@@ -38,14 +38,12 @@
 #include "sds.h"
 
 typedef struct redisReader {
-    char *buf; /* read buffer */
-    int len; /* buffer length */
-    int avail; /* available bytes for consumption */
-    int pos; /* buffer cursor */
+    sds buf; /* read buffer */
+    unsigned int pos; /* buffer cursor */
 
     redisReply **rlist; /* list of items to process */
-    int rlen; /* list length */
-    int rpos; /* list cursor */
+    unsigned int rlen; /* list length */
+    unsigned int rpos; /* list cursor */
 } redisReader;
 
 static redisReply *redisReadReply(int fd);
@@ -105,9 +103,9 @@ static redisReply *redisIOError(void) {
     return createReplyObject(REDIS_REPLY_ERROR,sdsnew("I/O error"));
 }
 
-static char *readBytes(redisReader *r, int bytes) {
+static char *readBytes(redisReader *r, unsigned int bytes) {
     char *p;
-    if (r->len-r->pos >= bytes) {
+    if (sdslen(r->buf)-r->pos >= bytes) {
         p = r->buf+r->pos;
         r->pos += bytes;
         return p;
@@ -274,58 +272,98 @@ static int processItem(redisReader *r) {
 
 #define READ_BUFFER_SIZE 2048
 static redisReply *redisReadReply(int fd) {
+    void *reader = redisCreateReplyReader();
     redisReply *reply;
-    redisReader r;
-    int bytes;
+    char buf[1024];
+    int nread;
 
-    /* setup read buffer */
-    r.buf = malloc(READ_BUFFER_SIZE+1);
-    r.len = READ_BUFFER_SIZE;
-    r.avail = 0;
-    r.pos = 0;
-
-    /* setup list of items to process */
-    r.rlist = malloc(sizeof(redisReply*));
-    r.rlist[0] = createReplyObject(-1,NULL);
-    r.rlen = 1;
-    r.rpos = 0;
-
-    while (r.rpos < r.rlen) {
-        /* discard the buffer upto pos */
-        if (r.pos > 0) {
-            memmove(r.buf,r.buf+r.pos,r.len-r.pos);
-            r.avail -= r.pos;
-            r.pos = 0;
+    do {
+        if ((nread = read(fd,buf,sizeof(buf))) <= 0) {
+            reply = redisIOError();
+            break;
+        } else {
+            reply = redisFeedReplyReader(reader,buf,nread);
         }
+    } while (reply == NULL);
 
-        /* make sure there is room for at least BUFFER_SIZE */
-        if (r.len-r.avail < READ_BUFFER_SIZE) {
-            r.buf = realloc(r.buf,r.avail+READ_BUFFER_SIZE+1);
-            r.len = r.avail+READ_BUFFER_SIZE;
-        }
-
-        /* read from socket into buffer */
-        if ((bytes = read(fd,r.buf+r.avail,READ_BUFFER_SIZE)) <= 0) {
-            /* rlist[0] is the "root" reply object */
-            freeReplyObject(r.rlist[0]);
-            free(r.buf);
-            free(r.rlist);
-            return redisIOError();
-        }
-        r.avail += bytes;
-        r.buf[r.avail] = '\0';
-
-        /* process items in reply */
-        while (r.rpos < r.rlen)
-            if (processItem(&r) < 0)
-                break;
-    }
-    reply = r.rlist[0];
-    free(r.buf);
-    free(r.rlist);
+    redisFreeReplyReader(reader);
     return reply;
 }
 
+void *redisCreateReplyReader() {
+    redisReader *r = calloc(sizeof(redisReader),1);
+    r->buf = sdsempty();
+    return r;
+}
+
+void redisFreeReplyReader(void *reader) {
+    redisReader *r = reader;
+    if (r->buf != NULL) {
+        sdsfree(r->buf);
+    }
+    if (r->rlen > 0) {
+        freeReplyObject(r->rlist[0]);
+        free(r->rlist);
+    }
+    free(r);
+}
+
+void *redisFeedReplyReader(void *reader, char *buf, int len) {
+    redisReader *r = reader;
+
+    /* Check if we are able to do *something*. */
+    if (sdslen(r->buf) == 0 && (buf == NULL || len <= 0))
+        return NULL;
+
+    /* Copy the provided buffer. */
+    if (buf != NULL && len >= 1)
+        r->buf = sdscatlen(r->buf,buf,len);
+
+    /* Create first item to process when the item list is empty. */
+    if (r->rlen == 0) {
+        r->rlist = malloc(sizeof(redisReply*));
+        r->rlist[0] = createReplyObject(-1,NULL);
+        r->rlen = 1;
+        r->rpos = 0;
+    }
+
+    /* Process items in reply. */
+    while (r->rpos < r->rlen)
+        if (processItem(r) < 0)
+            break;
+
+    /* Discard the consumed part of the buffer. */
+    if (r->pos > 0) {
+        if (r->pos == sdslen(r->buf)) {
+            /* sdsrange has a quirck on this edge case. */
+            sdsfree(r->buf);
+            r->buf = sdsempty();
+        } else {
+            r->buf = sdsrange(r->buf,r->pos,sdslen(r->buf));
+        }
+        r->pos = 0;
+    }
+
+    /* Emit a reply when there is one. */
+    if (r->rpos == r->rlen) {
+        redisReply *reply = r->rlist[0];
+
+        /* Destroy the buffer when it is empty and is quite large. */
+        if (sdslen(r->buf) == 0 && sdsavail(r->buf) > 16*1024) {
+            sdsfree(r->buf);
+            r->buf = sdsempty();
+            r->pos = 0;
+        }
+
+        /* Free list of items to process. */
+        free(r->rlist);
+        r->rlen = r->rpos = 0;
+        return reply;
+    } else {
+        return NULL;
+    }
+}
+
 /* Helper function for redisCommand(). It's used to append the next argument
  * to the argument vector. */
 static void addArgument(sds a, char ***argv, int *argc) {

hiredis.h

@@ -51,5 +51,8 @@ typedef struct redisReply {
 redisReply *redisConnect(int *fd, const char *ip, int port);
 void freeReplyObject(redisReply *r);
 redisReply *redisCommand(int fd, const char *format, ...);
+void *redisCreateReplyReader();
+void redisFreeReplyReader(void *ptr);
+void *redisFeedReplyReader(void *reader, char *buf, int len);
 
 #endif