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[SIGAR-31] Improve truncation detection in FileTail

This commit is contained in:
Doug MacEachern 2007-01-20 01:37:45 +00:00
parent 5087f2d84b
commit 7ab5c14d77
2 changed files with 50 additions and 13 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
2007-01-19 Doug MacEachern <dougm@hyperic.com>
* [SIGAR-31] Improve truncation detection in FileTail
2007-01-18 Doug MacEachern <dougm@hyperic.com> 2007-01-18 Doug MacEachern <dougm@hyperic.com>
* Add EventLog.getLogNames() method * Add EventLog.getLogNames() method

57
bindings/java/src/org/hyperic/sigar/FileTail.java
View File

@ -22,7 +22,8 @@ import java.io.FileReader;
import java.io.IOException; import java.io.IOException;
import java.io.InputStreamReader; import java.io.InputStreamReader;
import java.io.Reader; import java.io.Reader;
import java.util.HashMap;
import org.apache.log4j.Logger;
public abstract class FileTail extends FileWatcher { public abstract class FileTail extends FileWatcher {
@ -32,7 +33,10 @@ public abstract class FileTail extends FileWatcher {
private boolean useSudo = private boolean useSudo =
"true".equals(System.getProperty(PROP_USE_SUDO)); "true".equals(System.getProperty(PROP_USE_SUDO));
private HashMap offsets = new HashMap(); private static final Logger log =
SigarLog.getLogger(FileTail.class.getName());
private static final boolean isDebug = log.isDebugEnabled();
public abstract void tail(FileInfo info, Reader reader); public abstract void tail(FileInfo info, Reader reader);
@ -46,7 +50,7 @@ public abstract class FileTail extends FileWatcher {
static void error(String name, Throwable exc) { static void error(String name, Throwable exc) {
String msg = name + ": " + exc.getMessage(); String msg = name + ": " + exc.getMessage();
SigarLog.getLogger(FileTail.class.getName()).error(msg, exc); log.error(msg, exc);
} }
public void onChange(FileInfo info) { public void onChange(FileInfo info) {
@ -61,9 +65,14 @@ public abstract class FileTail extends FileWatcher {
else { else {
reader = new FileReader(name); reader = new FileReader(name);
} }
reader.skip(getOffset(info));
long offset = getOffset(info);
if (offset > 0) {
reader.skip(offset);
}
tail(info, reader); tail(info, reader);
setOffset(info);
} catch (IOException e) { } catch (IOException e) {
error(name, e); error(name, e);
} finally { } finally {
@ -76,7 +85,9 @@ public abstract class FileTail extends FileWatcher {
public FileInfo add(String file) public FileInfo add(String file)
throws SigarException { throws SigarException {
FileInfo info = super.add(file); FileInfo info = super.add(file);
setOffset(info); if (isDebug) {
log.debug("add: " + file + "=" + info);
}
return info; return info;
} }
@ -87,13 +98,35 @@ public abstract class FileTail extends FileWatcher {
return info.modified(); return info.modified();
} }
private long getOffset(FileInfo info) { private long getOffset(FileInfo current) {
Long offset = (Long)this.offsets.get(info); FileInfo previous = current.getPreviousInfo();
return offset.longValue(); if (previous == null) {
} if (isDebug) {
log.debug(current.getName() + ": first stat");
}
return current.size;
}
private void setOffset(FileInfo info) { if (current.inode != previous.inode) {
this.offsets.put(info, new Long(info.size)); if (isDebug) {
log.debug(current.getName() + ": file inode changed");
}
return -1;
}
if (current.size < previous.size) {
if (isDebug) {
log.debug(current.getName() + ": file truncated");
}
return -1;
}
if (isDebug) {
long diff = current.size - previous.size;
log.debug(current.getName() + ": " + diff + " new bytes");
}
return previous.size;
} }
} }