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don't share the skip bytes buffer

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git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1908700 13f79535-47bb-0310-9956-ffa450edef68
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PJ Fanning 2023-03-25 00:47:15 +00:00
parent 98f5f248ad
commit 9e53a4f7c2
1 changed files with 3 additions and 10 deletions
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13
poi/src/main/java/org/apache/poi/util/IOUtils.java
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@ -46,7 +46,6 @@ public final class IOUtils {
* The default buffer size to use for the skip() methods.
*/
private static final int SKIP_BUFFER_SIZE = 2048;
private static byte[] SKIP_BYTE_BUFFER;
/**
* The current set global allocation limit override,
@ -520,18 +519,12 @@ public final class IOUtils {
if (toSkip == 0) {
return 0L;
}
/*
* N.B. no need to synchronize this because: - we don't care if the buffer is created multiple times (the data
* is ignored) - we always use the same size buffer, so if it is recreated it will still be OK (if the buffer
* size were variable, we would need to synch. to ensure some other thread did not create a smaller one)
*/
if (SKIP_BYTE_BUFFER == null) {
SKIP_BYTE_BUFFER = new byte[SKIP_BUFFER_SIZE];
}
// use dedicated buffer to avoid having other threads possibly access the bytes in a shared byte array
final byte[] skipBuffer = new byte[SKIP_BUFFER_SIZE];
long remain = toSkip;
while (remain > 0) {
// See https://issues.apache.org/jira/browse/IO-203 for why we use read() rather than delegating to skip()
final long n = input.read(SKIP_BYTE_BUFFER, 0, (int) Math.min(remain, SKIP_BUFFER_SIZE));
final long n = input.read(skipBuffer, 0, (int) Math.min(remain, SKIP_BUFFER_SIZE));
if (n < 0) { // EOF
break;
}