From 6bb6cdaea7c08c3a68926f0cdd561f0d6bc5c81b Mon Sep 17 00:00:00 2001
From: Andreas Huber <bitbucket@lucares.de>
Date: Sun, 20 Sep 2020 19:51:47 +0200
Subject: [PATCH] count disk reads

---
 .../lucares/pdb/diskstorage/DiskStorage.java  |  3 +++
 .../pdb/diskstorage/DiskStoreStats.java       | 24 +++++++++++++++++++
 .../pdb/datastore/internal/DataStore.java     |  6 +++++
 3 files changed, 33 insertions(+)
 create mode 100644 block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStoreStats.java

diff --git a/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStorage.java b/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStorage.java
index e70d5a5..36436d5 100644
--- a/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStorage.java
+++ b/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStorage.java
@@ -53,6 +53,7 @@ public class DiskStorage implements AutoCloseable {
         try {
             LOGGER.trace("read block={} file={}", blockOffset, relativeDatabaseFileForLogging);
 
+            DiskStoreStats.incrementDiskRead();
             final var byteBuffer = fileChannel.map(MapMode.READ_WRITE, blockOffset, blockSize);
 
             return new DiskBlock(blockOffset, byteBuffer);
@@ -227,6 +228,7 @@ public class DiskStorage implements AutoCloseable {
 
     private FreeListNode readFreeListNode(final long freeListNodePosition) throws IOException {
         final var freeListNode = ByteBuffer.allocate(FREE_LIST_NODE_SIZE);
+        DiskStoreStats.incrementDiskRead();
         fileChannel.read(freeListNode, freeListNodePosition);
         final long offset = freeListNodePosition;
         final long next = freeListNode.getLong(FREE_LIST_NEXT_POINTER);
@@ -250,6 +252,7 @@ public class DiskStorage implements AutoCloseable {
 
     private long readFreeListRootNodePosition() throws IOException {
         final var freeListFirstBlock = ByteBuffer.allocate(8);
+        DiskStoreStats.incrementDiskRead();
         fileChannel.read(freeListFirstBlock, FREE_LIST_ROOT_OFFSET);
         return freeListFirstBlock.getLong(0);
     }
diff --git a/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStoreStats.java b/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStoreStats.java
new file mode 100644
index 0000000..7de30d9
--- /dev/null
+++ b/block-storage/src/main/java/org/lucares/pdb/diskstorage/DiskStoreStats.java
@@ -0,0 +1,24 @@
+package org.lucares.pdb.diskstorage;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+public class DiskStoreStats {
+    private static final AtomicLong diskRead = new AtomicLong(0);
+
+    public static void incrementDiskRead() {
+        diskRead.incrementAndGet();
+    }
+
+    public static void resetDiskRead() {
+        diskRead.set(0);
+    }
+
+    public static long getDiskRead() {
+        return diskRead.get();
+    }
+
+    public static long getAndResetDiskRead() {
+
+        return diskRead.getAndSet(0);
+    }
+}
diff --git a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
index a53019e..a908994 100644
--- a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
+++ b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
@@ -32,6 +32,7 @@ import org.lucares.pdb.datastore.lang.Expression;
 import org.lucares.pdb.datastore.lang.ExpressionToDocIdVisitor;
 import org.lucares.pdb.datastore.lang.NewProposerParser;
 import org.lucares.pdb.datastore.lang.QueryLanguageParser;
+import org.lucares.pdb.diskstorage.DiskStoreStats;
 import org.lucares.pdb.map.PersistentMap;
 import org.lucares.utils.Preconditions;
 import org.lucares.utils.cache.HotEntryCache;
@@ -235,11 +236,16 @@ public class DataStore implements AutoCloseable {
 
     public List<Doc> search(final Query query) {
         try {
+            DiskStoreStats.resetDiskRead();
             final List<Doc> result = new ArrayList<>();
 
             final PartitionLongList docIdsList = executeQuery(query);
             LOGGER.trace("query {} found {} docs", query, docIdsList.size());
+
+            DiskStoreStats.incrementDiskRead();
+            LOGGER.info("Disk reads - search {}", DiskStoreStats.getAndResetDiskRead());
             final List<Doc> docs = mapDocIdsToDocs(docIdsList);
+            LOGGER.info("Disk reads - mappedToDocIds {}", DiskStoreStats.getAndResetDiskRead());
             result.addAll(docs);
 
             return result;