From 8cc92d896d1610365e7d5ff7bfecdc8fe86ae9a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20Borgstr=C3=B6m?= <jonas@borgstrom.se>
Date: Sat, 22 Jun 2013 19:51:07 +0200
Subject: [PATCH] Avoid unnecessary reads when we've already reached EOF.
---
darc/_chunker.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/darc/_chunker.c b/darc/_chunker.c
index d4fca7106..470025b8d 100644
--- a/darc/_chunker.c
+++ b/darc/_chunker.c
@@ -78,7 +78,7 @@ typedef struct {
uint32_t *table;
uint8_t *data;
PyObject *fd;
- int done;
+ int done, eof;
size_t remaining, bytes_read, bytes_yielded, position, last;
} Chunker;
@@ -100,6 +100,7 @@ chunker_init(PyObject *fd, int window_size, int chunk_mask, int min_size, uint32
c->bytes_yielded = 0;
c->position = 0;
c->last = 0;
+ c->eof = 0;
return c;
}
@@ -118,14 +119,22 @@ chunker_fill(Chunker *c)
memmove(c->data, c->data + c->last, c->position + c->remaining - c->last);
c->position -= c->last;
c->last = 0;
+ if(c->eof) {
+ return 1;
+ }
PyObject *data = PyObject_CallMethod(c->fd, "read", "i", c->buf_size - c->position - c->remaining);
if(!data) {
return 0;
}
int n = PyBytes_Size(data);
- memcpy(c->data + c->position + c->remaining, PyBytes_AsString(data), n);
- c->remaining += n;
- c->bytes_read += n;
+ if(n) {
+ memcpy(c->data + c->position + c->remaining, PyBytes_AsString(data), n);
+ c->remaining += n;
+ c->bytes_read += n;
+ }
+ else {
+ c->eof = 1;
+ }
Py_DECREF(data);
return 1;
}
@@ -176,7 +185,7 @@ chunker_process(Chunker *c)
}
}
sum = buzhash(c->data + c->position, window_size, c->table);
- while(c->remaining >= c->window_size && ((sum & chunk_mask) || n < min_size)) {
+ while(c->remaining > c->window_size && ((sum & chunk_mask) || n < min_size)) {
sum = buzhash_update(sum, c->data[c->position],
c->data[c->position + window_size],
window_size, c->table);