Recent changes to DiskCache_Implemented

DiskCache_Implemented modified by silex6

silex6 — Fri, 20 Jun 2025 08:27:18 -0000

--- v4
+++ v5
@@ -17,3 +17,6 @@
 Memory mapping has not been implemented. Initial implementation led to many OutOfMemoryError. The implementation was then changed to use a HashMap to keep copies of the page into memory - into Java runtime's heap space

 Copy-on-write and shadow copies feature is implemented by *file container* layer
+
+#See also 
+[Disk cache](Disk_cache) specification

DiskCache_Implemented modified by silex6

silex6 — Fri, 20 Jun 2025 07:54:27 -0000

--- v3
+++ v4
@@ -2,7 +2,7 @@
 This database software stack implements disk caching. This feature allows to manipulate huge files, minimize the number of time consuming I/O operation and remove the need to keep complete file into memory. The disk caching API provide paged access to a database file via the *Cache* and *Page* interfaces.

 The disk cache package org.whitebear.cache is stable since 2021
-#Main classes
+#Main interfaces
 * Cache - provide cached access to a pages file
 * Page - provide access to a file page. Current page size in 8kb
 * BufferReaderWriter - allow to read / write page content

DiskCache_Implemented modified by silex6

silex6 — Thu, 19 Jun 2025 11:42:30 -0000

--- v2
+++ v3
@@ -1,5 +1,5 @@
 # Disk cache
-This database software stack implements disk caching. This allow to manipulate huge files, minimize the number of time consuming I/O operation and remove the need to keep complete file into memory. The disk caching API provide paged access to a database file via the *Cache* and *Page* interfaces.
+This database software stack implements disk caching. This feature allows to manipulate huge files, minimize the number of time consuming I/O operation and remove the need to keep complete file into memory. The disk caching API provide paged access to a database file via the *Cache* and *Page* interfaces.

 The disk cache package org.whitebear.cache is stable since 2021
 #Main classes

DiskCache_Implemented modified by silex6

silex6 — Thu, 19 Jun 2025 10:18:14 -0000

--- v1
+++ v2
@@ -1,5 +1,5 @@
 # Disk cache
-This database software stack implements disk caching. This allow to manipulate huge files without the need to keep complete file into memory. The disk caching API provide paged access to a database file via the *Cache* and *Page* interfaces.
+This database software stack implements disk caching. This allow to manipulate huge files, minimize the number of time consuming I/O operation and remove the need to keep complete file into memory. The disk caching API provide paged access to a database file via the *Cache* and *Page* interfaces.

 The disk cache package org.whitebear.cache is stable since 2021
 #Main classes
@@ -10,8 +10,10 @@
 * LockList - allow to lock a set of pages in an single atomic operation

 #Current implementation
-Current disk cache implementation use java.io.RandomAccessFile to access the database file. The disk cache uses java.nio.ByteBuffer to retain in-memory copies of disk content.
+Current disk cache implementation use java.io.RandomAccessFile to access the database file. The disk cache uses java.nio.ByteBuffer to retain in-memory copies of disk content. All classes are thread-safe

-A background thread is responsible to remove unused pages from memory. It implements a 2nd chance algorithm
+*CacheCleanupThread* is a background thread responsible to remove unused pages from memory. It implements a 2nd chance algorithm

 Memory mapping has not been implemented. Initial implementation led to many OutOfMemoryError. The implementation was then changed to use a HashMap to keep copies of the page into memory - into Java runtime's heap space
+
+Copy-on-write and shadow copies feature is implemented by *file container* layer

DiskCache_Implemented modified by silex6

silex6 — Thu, 19 Jun 2025 10:10:39 -0000

Disk cache

This database software stack implements disk caching. This allow to manipulate huge files without the need to keep complete file into memory. The disk caching API provide paged access to a database file via the Cache and Page interfaces.

The disk cache package org.whitebear.cache is stable since 2021

Main classes

Cache - provide cached access to a pages file
Page - provide access to a file page. Current page size in 8kb
BufferReaderWriter - allow to read / write page content
WriteList - keep list of pages that need to be written back to the hard disk - actually to the operating system
LockList - allow to lock a set of pages in an single atomic operation

Current implementation

Current disk cache implementation use java.io.RandomAccessFile to access the database file. The disk cache uses java.nio.ByteBuffer to retain in-memory copies of disk content.

A background thread is responsible to remove unused pages from memory. It implements a 2nd chance algorithm

Memory mapping has not been implemented. Initial implementation led to many OutOfMemoryError. The implementation was then changed to use a HashMap to keep copies of the page into memory - into Java runtime's heap space