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8223490: Optimize search algorithm for determining default time zone

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Reviewed-by: naoto, rriggs
This commit is contained in:
Sean Coffey 2019-09-17 11:07:07 +00:00
parent 89b0250e4a
commit 788b2414c1
1 changed files with 71 additions and 45 deletions
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116
src/java.base/unix/native/libjava/TimeZone_md.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -42,6 +42,8 @@
#include "jvm.h"
#include "TimeZone_md.h"
static char *isFileIdentical(char* buf, size_t size, char *pathname);
#define SKIP_SPACE(p) while (*p == ' ' || *p == '\t') p++;
#define RESTARTABLE(_cmd, _result) do { \
@ -72,6 +74,8 @@ static const char *ZONEINFO_DIR = "/usr/share/lib/zoneinfo";
static const char *DEFAULT_ZONEINFO_FILE = "/usr/share/lib/zoneinfo/localtime";
#endif /* defined(__linux__) || defined(_ALLBSD_SOURCE) */
static const char popularZones[][4] = {"UTC", "GMT"};
#if defined(_AIX)
static const char *ETC_ENVIRONMENT_FILE = "/etc/environment";
#endif
@ -121,11 +125,8 @@ static char *
findZoneinfoFile(char *buf, size_t size, const char *dir)
{
DIR *dirp = NULL;
struct stat64 statbuf;
struct dirent *dp = NULL;
char *pathname = NULL;
int fd = -1;
char *dbuf = NULL;
char *tz = NULL;
int res;
@ -134,6 +135,22 @@ findZoneinfoFile(char *buf, size_t size, const char *dir)
return NULL;
}
if (strcmp(dir, ZONEINFO_DIR) == 0) {
/* fast path for 1st iteration */
for (unsigned int i = 0; i < sizeof (popularZones) / sizeof (popularZones[0]); i++) {
pathname = getPathName(dir, popularZones[i]);
if (pathname == NULL) {
continue;
}
tz = isFileIdentical(buf, size, pathname);
free((void *) pathname);
pathname = NULL;
if (tz != NULL) {
return tz;
}
}
}
while ((dp = readdir(dirp)) != NULL) {
/*
* Skip '.' and '..' (and possibly other .* files)
@ -162,58 +179,67 @@ findZoneinfoFile(char *buf, size_t size, const char *dir)
if (pathname == NULL) {
break;
}
RESTARTABLE(stat64(pathname, &statbuf), res);
if (res == -1) {
break;
}
if (S_ISDIR(statbuf.st_mode)) {
tz = findZoneinfoFile(buf, size, pathname);
if (tz != NULL) {
break;
}
} else if (S_ISREG(statbuf.st_mode) && (size_t)statbuf.st_size == size) {
dbuf = (char *) malloc(size);
if (dbuf == NULL) {
break;
}
RESTARTABLE(open(pathname, O_RDONLY), fd);
if (fd == -1) {
break;
}
RESTARTABLE(read(fd, dbuf, size), res);
if (res != (ssize_t) size) {
break;
}
if (memcmp(buf, dbuf, size) == 0) {
tz = getZoneName(pathname);
if (tz != NULL) {
tz = strdup(tz);
}
break;
}
free((void *) dbuf);
dbuf = NULL;
(void) close(fd);
fd = -1;
}
tz = isFileIdentical(buf, size, pathname);
free((void *) pathname);
pathname = NULL;
if (tz != NULL) {
break;
}
}
if (dirp != NULL) {
(void) closedir(dirp);
}
if (pathname != NULL) {
free((void *) pathname);
return tz;
}
/*
* Checks if the file pointed to by pathname matches
* the data contents in buf.
* Returns a representation of the timezone file name
* if file match is found, otherwise NULL.
*/
static char *
isFileIdentical(char *buf, size_t size, char *pathname)
{
char *possibleMatch = NULL;
struct stat64 statbuf;
char *dbuf = NULL;
int fd = -1;
int res;
RESTARTABLE(stat64(pathname, &statbuf), res);
if (res == -1) {
return NULL;
}
if (fd != -1) {
if (S_ISDIR(statbuf.st_mode)) {
possibleMatch = findZoneinfoFile(buf, size, pathname);
} else if (S_ISREG(statbuf.st_mode) && (size_t)statbuf.st_size == size) {
dbuf = (char *) malloc(size);
if (dbuf == NULL) {
return NULL;
}
RESTARTABLE(open(pathname, O_RDONLY), fd);
if (fd == -1) {
goto freedata;
}
RESTARTABLE(read(fd, dbuf, size), res);
if (res != (ssize_t) size) {
goto freedata;
}
if (memcmp(buf, dbuf, size) == 0) {
possibleMatch = getZoneName(pathname);
if (possibleMatch != NULL) {
possibleMatch = strdup(possibleMatch);
}
}
freedata:
free((void *) dbuf);
(void) close(fd);
}
if (dbuf != NULL) {
free((void *) dbuf);
}
return tz;
return possibleMatch;
}
#if defined(__linux__) || defined(MACOSX)