Fix protocol error (#1106)

Fix ProtocolError

This commit attempts to fix hiredis such that a recoverable write error
will be retried rather than throwing a hard error.

Since our read/write functions are now behind function pointers, we
specify semantically that a return value of < 0 is a hard error, 0 a
recoverable error, and > 0 a success.

Our default `redisNetRead` function was already doing something similar
so this also improves code consistency.

Resolves #961

Co-authored-by: Maksim Tuleika <maksim.tuleika@appcast.io>

1 files changed, 6 insertions, 0 deletions

diff --git a/hiredis.h b/hiredis.h
index 5969368..0a17495 100644
--- a/hiredis.h
+++ b/hiredis.h
@@ -249,10 +249,16 @@ typedef struct redisContextFuncs {
     void (*free_privctx)(void *);
     void (*async_read)(struct redisAsyncContext *);
     void (*async_write)(struct redisAsyncContext *);
+
+    /* Read/Write data to the underlying communication stream, returning the
+     * number of bytes read/written.  In the event of an unrecoverable error
+     * these functions shall return a value < 0.  In the event of a
+     * recoverable error, they should return 0. */
     ssize_t (*read)(struct redisContext *, char *, size_t);
     ssize_t (*write)(struct redisContext *);
 } redisContextFuncs;
 
+
 /* Context for a connection to Redis */
 typedef struct redisContext {
     const redisContextFuncs *funcs;   /* Function table */