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authorJunio C Hamano <gitster@pobox.com>2008-11-13 05:51:30 (GMT)
committerJunio C Hamano <gitster@pobox.com>2008-11-13 05:51:30 (GMT)
commitac2abb49ce1afdb0ba5b52bb18d04671a325c6c0 (patch)
tree3c095c76f8479f4cc701061a455c856651741246 /xdiff
parentb2b80c107f6db4c3297af59fd2fb40ada5899778 (diff)
parent9b28d55401a529ff08c709f42f66e765c93b0a20 (diff)
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Merge branch 'dl/xdiff'
* dl/xdiff: xdiff: give up scanning similar lines early
Diffstat (limited to 'xdiff')
-rw-r--r--xdiff/xprepare.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c
index e87ab57..a43aa72 100644
--- a/xdiff/xprepare.c
+++ b/xdiff/xprepare.c
@@ -23,10 +23,9 @@
#include "xinclude.h"
-
#define XDL_KPDIS_RUN 4
#define XDL_MAX_EQLIMIT 1024
-
+#define XDL_SIMSCAN_WINDOW 100
typedef struct s_xdlclass {
@@ -313,6 +312,18 @@ static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
long r, rdis0, rpdis0, rdis1, rpdis1;
/*
+ * Limits the window the is examined during the similar-lines
+ * scan. The loops below stops when dis[i - r] == 1 (line that
+ * has no match), but there are corner cases where the loop
+ * proceed all the way to the extremities by causing huge
+ * performance penalties in case of big files.
+ */
+ if (i - s > XDL_SIMSCAN_WINDOW)
+ s = i - XDL_SIMSCAN_WINDOW;
+ if (e - i > XDL_SIMSCAN_WINDOW)
+ e = i + XDL_SIMSCAN_WINDOW;
+
+ /*
* Scans the lines before 'i' to find a run of lines that either
* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
* Note that we always call this function with dis[i] > 1, so the