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Improve DiskLruCache

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This commit is contained in:
carbotaniuman 2020-06-12 09:50:49 -05:00
parent 2d756d7c7c
commit c302bf6d67
1 changed files with 37 additions and 68 deletions
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105
src/main/java/mdnet/cache/DiskLruCache.java vendored
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@ -82,9 +82,10 @@ import java.util.regex.Pattern;
* <li>When an entry is being <strong>edited</strong>, it is not necessary to
* supply data for every value; values default to their previous value.
* </ul>
* Every {@link #editImpl} call must be matched by a call to {@link Editor#commit}
* or {@link Editor#abort}. Committing is atomic: a read observes the full set
* of values as they were before or after the commit, but never a mix of values.
* Every {@link #editImpl} call must be matched by a call to
* {@link Editor#commit} or {@link Editor#abort}. Committing is atomic: a read
* observes the full set of values as they were before or after the commit, but
* never a mix of values.
*
* <p>
* Clients call {@link #get} to read a snapshot of an entry. The read will
@ -110,7 +111,6 @@ public final class DiskLruCache implements Closeable {
private static final long ANY_SEQUENCE_NUMBER = -1;
public static final Pattern LEGAL_KEY_PATTERN = Pattern.compile("[a-z0-9_-]{1,120}");
public static final Pattern UNSAFE_LEGAL_KEY_PATTERN = Pattern.compile("[a-z0-9_-][\\/a-z0-9_-]{0,119}");
private static final String CLEAN = "CLEAN";
private static final String DIRTY = "DIRTY";
@ -412,16 +412,6 @@ public final class DiskLruCache implements Closeable {
return getImpl(key);
}
/**
* Returns a snapshot of the entry named {@code key}, or null if it doesn't
* exist is not currently readable. If a value is returned, it is moved to the
* head of the LRU queue. Unsafe as it allows arbitrary directories to be accessed!
*/
public Snapshot getUnsafe(String key) throws IOException {
validateUnsafeKey(key);
return getImpl(key);
}
public synchronized Snapshot getImpl(String key) throws IOException {
checkNotClosed();
Entry entry = lruEntries.get(key);
@ -474,15 +464,6 @@ public final class DiskLruCache implements Closeable {
return editImpl(key, ANY_SEQUENCE_NUMBER);
}
/**
* Returns an editor for the entry named {@code key}, or null if another edit is
* in progress. Unsafe as it allows arbitrary directories to be accessed!
*/
public Editor editUnsafe(String key) throws IOException {
validateUnsafeKey(key);
return editImpl(key, ANY_SEQUENCE_NUMBER);
}
private synchronized Editor editImpl(String key, long expectedSequenceNumber) throws IOException {
checkNotClosed();
Entry entry = lruEntries.get(key);
@ -614,17 +595,6 @@ public final class DiskLruCache implements Closeable {
return removeImpl(key);
}
/**
* Drops the entry for {@code key} if it exists and can be removed. Entries
* actively being edited cannot be removed. Unsafe as it allows arbitrary directories to be accessed!
*
* @return true if an entry was removed.
*/
public boolean removeUnsafe(String key) throws IOException {
validateUnsafeKey(key);
return removeImpl(key);
}
private synchronized boolean removeImpl(String key) throws IOException {
checkNotClosed();
Entry entry = lruEntries.get(key);
@ -709,13 +679,6 @@ public final class DiskLruCache implements Closeable {
}
}
private void validateUnsafeKey(String key) {
Matcher matcher = UNSAFE_LEGAL_KEY_PATTERN.matcher(key);
if (!matcher.matches()) {
throw new IllegalArgumentException("keys must match regex " + UNSAFE_LEGAL_KEY_PATTERN + ": \"" + key + "\"");
}
}
/** A snapshot of the values for an entry. */
public final class Snapshot implements Closeable {
private final String key;
@ -790,7 +753,7 @@ public final class DiskLruCache implements Closeable {
* Returns an unbuffered input stream to read the last committed value, or null
* if no value has been committed.
*/
public InputStream newInputStream(int index) {
public synchronized InputStream newInputStream(int index) {
synchronized (DiskLruCache.this) {
if (entry.currentEditor != this) {
throw new IllegalStateException();
@ -806,32 +769,13 @@ public final class DiskLruCache implements Closeable {
}
}
/**
* Returns the last committed value as a string, or null if no value has been
* committed.
*/
public String getString(int index) throws IOException {
try (InputStream in = newInputStream(index)) {
return in != null ? IOUtils.toString(in, StandardCharsets.UTF_8) : null;
}
}
/**
* Write a string to the specified index.
*/
public void setString(int index, String value) throws IOException {
try (OutputStream out = newOutputStream(index)) {
IOUtils.write(value, out, StandardCharsets.UTF_8);
}
}
/**
* Returns a new unbuffered output stream to write the value at {@code index}.
* If the underlying output stream encounters errors when writing to the
* filesystem, this edit will be aborted when {@link #commit} is called. The
* returned output stream does not throw IOExceptions.
*/
public OutputStream newOutputStream(int index) {
public synchronized OutputStream newOutputStream(int index) {
if (index < 0 || index >= valueCount) {
throw new IllegalArgumentException("Expected index " + index + " to "
+ "be greater than 0 and less than the maximum value count " + "of " + valueCount);
@ -862,6 +806,25 @@ public final class DiskLruCache implements Closeable {
}
}
/**
* Returns the last committed value as a string, or null if no value has been
* committed.
*/
public String getString(int index) throws IOException {
try (InputStream in = newInputStream(index)) {
return in != null ? IOUtils.toString(in, StandardCharsets.UTF_8) : null;
}
}
/**
* Write a string to the specified index.
*/
public void setString(int index, String value) throws IOException {
try (OutputStream out = newOutputStream(index)) {
IOUtils.write(value, out, StandardCharsets.UTF_8);
}
}
/**
* Commits this edit so it is visible to readers. This releases the edit lock so
* another edit may be started on the same key.
@ -966,8 +929,10 @@ public final class DiskLruCache implements Closeable {
this.key = key;
this.lengths = new long[valueCount];
// Splits the keys into a list of two characters, and join it together to use it for sub-directorying
this.subKeyPath = File.separator + String.join(File.separator, key.substring(0, 8).replaceAll("..(?!$)", "$0 ").split(" "));
// Splits the keys into a list of two characters, and join it together to use it
// for sub-directorying
this.subKeyPath = File.separator
+ String.join(File.separator, key.substring(0, 8).replaceAll("..(?!$)", "$0 ").split(" "));
}
public String getLengths() {
@ -1007,8 +972,10 @@ public final class DiskLruCache implements Closeable {
} catch (FileAlreadyExistsException faee) {
try {
Files.delete(oldCache);
} catch (IOException ex) {}
} catch (IOException ex) {}
} catch (IOException ex) {
}
} catch (IOException ex) {
}
}
return new File(directory + subKeyPath, key + "." + i);
@ -1024,8 +991,10 @@ public final class DiskLruCache implements Closeable {
} catch (FileAlreadyExistsException faee) {
try {
Files.delete(oldCache);
} catch (IOException ex) {}
} catch (IOException ex) {}
} catch (IOException ex) {
}
} catch (IOException ex) {
}
}
return new File(directory + subKeyPath, key + "." + i + ".tmp");