Merge pull request libgit2#4311 from libgit2/ethomson/win32_remediate

win32: provide fast-path for retrying filesystem operations

Author: ethomson

CHANGELOG.md

@@ -3,6 +3,9 @@ v0.26 + 1
 
 ### Changes or improvements
 
+* Improved `p_unlink` in `posix_w32.c` to try and make a file writable
+  before sleeping in the retry loop to prevent unnecessary calls to sleep.
+
 ### API additions
 
 ### API removals

src/win32/posix_w32.c

@@ -162,12 +162,15 @@ GIT_INLINE(bool) last_error_retryable(void)
 
 #define do_with_retries(fn, remediation) \
 	do {                                                             \
-		int __tries, __ret;                                          \
-		for (__tries = 0; __tries < git_win32__retries; __tries++) { \
-			if (__tries && (__ret = (remediation)) != 0)             \
-				return __ret;                                        \
+		int __retry, __ret;                                          \
+		for (__retry = git_win32__retries; __retry; __retry--) {     \
 			if ((__ret = (fn)) != GIT_RETRY)                         \
 				return __ret;                                        \
+			if (__retry > 1 && (__ret = (remediation)) != 0) {       \
+				if (__ret == GIT_RETRY)                              \
+					continue;                                        \
+				return __ret;                                        \
+			}                                                        \
 			Sleep(5);                                                \
 		}                                                            \
 		return -1;                                                   \
@@ -186,7 +189,7 @@ static int ensure_writable(wchar_t *path)
 	if (!SetFileAttributesW(path, (attrs & ~FILE_ATTRIBUTE_READONLY)))
 		goto on_error;
 
-	return 0;
+	return GIT_RETRY;
 
 on_error:
 	set_errno();