reftable: support threshold based compaction
Transactions may wish to merge several tables together as part of an
operation. Setting a byte limit allows the transaction to consider
only some recent tables, bounding the cost of the compaction.
Change-Id: If037f2cbdc174ff1a215d5917178b33cde4ddaba
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java
index a91cdc8..4f92267 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableCompactor.java
@@ -71,6 +71,8 @@
private final ReftableWriter writer = new ReftableWriter();
private final ArrayDeque<Reftable> tables = new ArrayDeque<>();
+ private long compactBytesLimit;
+ private long bytesToCompact;
private boolean includeDeletes;
private long minUpdateIndex;
private long maxUpdateIndex;
@@ -88,6 +90,16 @@
}
/**
+ * @param bytes
+ * limit on number of bytes from source tables to compact.
+ * @return {@code this}
+ */
+ public ReftableCompactor setCompactBytesLimit(long bytes) {
+ compactBytesLimit = bytes;
+ return this;
+ }
+
+ /**
* @param deletes
* {@code true} to include deletions in the output, which may be
* necessary for partial compaction.
@@ -139,6 +151,9 @@
/**
* Add all of the tables, in the specified order.
+ * <p>
+ * Unconditionally adds all tables, ignoring the
+ * {@link #setCompactBytesLimit(long)}.
*
* @param readers
* tables to compact. Tables should be ordered oldest first/most
@@ -150,6 +165,32 @@
}
/**
+ * Try to add this reader at the bottom of the stack.
+ * <p>
+ * A reader may be rejected by returning {@code false} if the compactor is
+ * already rewriting its {@link #setCompactBytesLimit(long)}. When this
+ * happens the caller should stop trying to add tables, and execute the
+ * compaction.
+ *
+ * @param reader
+ * the reader to insert at the bottom of the stack. Caller is
+ * responsible for closing the reader.
+ * @return {@code true} if the compactor accepted this table; {@code false}
+ * if the compactor has reached its limit.
+ * @throws IOException
+ * if size of {@code reader} cannot be read.
+ */
+ public boolean tryAddFirst(ReftableReader reader) throws IOException {
+ long sz = reader.size();
+ if (compactBytesLimit > 0 && bytesToCompact + sz > compactBytesLimit) {
+ return false;
+ }
+ bytesToCompact += sz;
+ tables.addFirst(reader);
+ return true;
+ }
+
+ /**
* Write a compaction to {@code out}.
*
* @param out
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableReader.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableReader.java
index 3d505e3..be1eb40 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableReader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/reftable/ReftableReader.java
@@ -433,6 +433,17 @@
return end % blockSize == 0 ? blocks : (blocks + 1);
}
+ /**
+ * Get size of the reftable, in bytes.
+ *
+ * @return size of the reftable, in bytes.
+ * @throws IOException
+ * size cannot be obtained.
+ */
+ public long size() throws IOException {
+ return src.size();
+ }
+
@Override
public void close() throws IOException {
src.close();
