---------------------
PatchSet 7788 
Date: 2008/04/21 12:53:58
Author: amosjeffries
Branch: docs
Tag: (none) 
Log:
FileSystem API docs moved to .h

Members: 
	src/fs/FileSystems.dox:1.1.2.6->1.1.2.7(DEAD) 

--- squid3/src/fs/FileSystems.dox	2008-04-22 00:27:31.232372941 +0000
+++ /dev/null	2008-04-22 00:27:31.000000000 +0000
@@ -1,87 +0,0 @@
-/**
-\defgroup FileSystems	Storage Filesystems
-
-\section Introduction Introduction
-\par
-	Traditionally, Squid has always used the Unix filesystem (\link UFS UFS\endlink)
-	to store cache objects on disk.  Over the years, the
-	poor performance of \link UFS UFS\endlink has become very obvious.  In most
-	cases, \link UFS UFS\endlink limits Squid to about 30-50 requests per second.
-	Our work indicates that the poor performance is mostly
-	due to the synchronous nature of open() and unlink()
-	system calls, and perhaps thrashing of inode/buffer caches.
-
-\par
-	We want to try out our own, customized filesystems with Squid.
-	In order to do that, we need a well-defined interface
-	for the bits of Squid that access the permanent storage
-	devices. We also require tighter control of the replacement
-	policy by each storage module, rather than a single global
-	replacement policy.
-
-\section BuildStructure Build structure
-\par
-	The storage types live in \em src/fs/. Each subdirectory corresponds
-	to the name of the storage type. When a new storage type is implemented
-	configure.in must be updated to autogenerate a Makefile in
-	\em src/fs/foo/ from a Makefile.in file.
-\todo DOCS: add template addition to configure.in for storage module addition.
-\todo DOCS: add template Makefile.am for storage module addition.
-
-\par
-	configure will take a list of storage types through the
-	--enable-store-io parameter. This parameter takes a list of
-	space seperated storage types. For example,
-	--enable-store-io="ufs coss" .
-
-\par
-	Each storage type must create an archive file
-	in \em src/fs/foo/.a . This file is automatically linked into
-	squid at compile time.
-
-\par
-	Each storefs must export a function named \em storeFsSetup_foo().
-	This function is called at runtime to initialise each storage type.
-	The list of storage types is passed through store_modules.sh
-	to generate the initialisation function storeFsSetup(). This
-	function lives in store_modules.c.
-\todo DOCS: find out what has replaced storeFsSetup() and store_modules.c
-\todo DOCS: find out what has replaced storefs
-
-\par Example of the automatically generated file:
-\code
-	// automatically generated by ./store_modules.sh ufs coss do not edit
-
-	#include "squid.h"
-
-	extern STSETUP storeFsSetup_ufs;
-	extern STSETUP storeFsSetup_coss;
-	void storeFsSetup(void)
-	{
-		storeFsAdd("ufs", storeFsSetup_ufs);
-		storeFsAdd("coss", storeFsSetup_coss);
-	}
-\endcode
-\todo DOCS: find out what has replaced storeFSAdd
-\todo DOCS: find out what has replaced storeFSSetup and storeFSSetup_*
-
-\section OperationOfStorageModules Operation of a Storage Module
-\par
-	Squid understands the concept of multiple diverse storage directories.
-	Each storage directory provides a caching object store, with object
-	storage, retrieval, indexing and replacement.
-
-\par
-	Each open object has associated with it a storeIOState object. The
-	storeIOState object is used to record the state of the current
-	object. Each storeIOState can have a storage module specific data
-	structure containing information private to the storage module.
-
-\par
-	Each SwapDir has the concept of a maximum object size. This is used
-	as a basic hint to the storage layer in first choosing a suitable
-	SwapDir. The checkobj function is then called for suitable
-	candidate SwapDirs to find out whether it wants to store a
-	given StoreEntry. A maxobjsize of -1 means 'any size'.
-
- */