Minor cleanups to the header comments on various test_*.c file, to make

the suitable for programmer-level documentation.

FossilOrigin-Name: a65d043a2ad895b931871c67e0ef397a1dc614a6

4 files changed, 39 insertions, 23 deletions

diff --git a/src/test_demovfs.c b/src/test_demovfs.c
index d7bcd1f90..637627071 100644
--- a/src/test_demovfs.c
+++ b/src/test_demovfs.c
@@ -10,14 +10,12 @@
 **
 *************************************************************************
 **
-** An example of a simple VFS implementation that omits complex features
-** often not required or not possible on embedded platforms. Also includes
-** code to buffer writes to the journal file, which can be a significant
-** performance improvement on some embedded platforms.
+** This file implements an example of a simple VFS implementation that 
+** omits complex features often not required or not possible on embedded
+** platforms.  Code is included to buffer writes to the journal file, 
+** which can be a significant performance improvement on some embedded
+** platforms.
 **
-*/
-
-/*
 ** OVERVIEW
 **
 **   The code in this file implements a minimal SQLite VFS that can be 
diff --git a/src/test_journal.c b/src/test_journal.c
index ca4c5c388..68869723b 100644
--- a/src/test_journal.c
+++ b/src/test_journal.c
@@ -14,13 +14,7 @@
 ** an existing VFS. The code in this file attempts to verify that SQLite
 ** correctly populates and syncs a journal file before writing to a
 ** corresponding database file.
-*/
-#if SQLITE_TEST          /* This file is used for testing only */
-
-#include "sqlite3.h"
-#include "sqliteInt.h"
-
-/*
+**
 ** INTERFACE
 **
 **   The public interface to this wrapper VFS is two functions:
@@ -99,6 +93,10 @@
 **
 **     c) The journal file is deleted using xDelete.
 */
+#if SQLITE_TEST          /* This file is used for testing only */
+
+#include "sqlite3.h"
+#include "sqliteInt.h"
 
 /*
 ** Maximum pathname length supported by the jt backend.
diff --git a/src/test_multiplex.c b/src/test_multiplex.c
index 32e63ae88..f709c9a99 100644
--- a/src/test_multiplex.c
+++ b/src/test_multiplex.c
@@ -11,13 +11,36 @@
 *************************************************************************
 **
 ** This file contains a VFS "shim" - a layer that sits in between the
-** pager and the real VFS.
+** pager and the real VFS - that breaks up a very large database file
+** into two or more smaller files on disk.  This is useful, for example,
+** in order to support large, multi-gigabyte databases on older filesystems
+** that limit the maximum file size to 2 GiB.
 **
-** This particular shim enforces a multiplex system on DB files.  
-** This shim shards/partitions a single DB file into smaller 
-** "chunks" such that the total DB file size may exceed the maximum
-** file size of the underlying file system.
+** USAGE:
 **
+** Compile this source file and link it with your application.  Then
+** at start-time, invoke the following procedure:
+**
+**   int sqlite3_multiplex_initialize(
+**      const char *zOrigVfsName,    // The underlying real VFS
+**      int makeDefault              // True to make multiplex the default VFS
+**   );
+**
+** The procedure call above will create and register a new VFS shim named
+** "multiplex".  The multiplex VFS will use the VFS named by zOrigVfsName to
+** do the actual disk I/O.  (The zOrigVfsName parameter may be NULL, in 
+** which case the default VFS at the moment sqlite3_multiplex_initialize()
+** is called will be used as the underlying real VFS.)  
+**
+** If the makeDefault parameter is TRUE then multiplex becomes the new
+** default VFS.  Otherwise, you can use the multiplex VFS by specifying
+** "multiplex" as the 4th parameter to sqlite3_open_v2() or by employing
+** URI filenames and adding "vfs=multiplex" as a parameter to the filename
+** URI.
+**
+** The multiplex VFS allows databases up to 32 GiB in size.  But it splits
+** the files up into 1 GiB pieces, so that they will work even on filesystems
+** that do not support large files.
 */
 #include "sqlite3.h"
 #include <string.h>
diff --git a/src/test_vfs.c b/src/test_vfs.c
index ba078a0f9..696321d26 100644
--- a/src/test_vfs.c
+++ b/src/test_vfs.c
@@ -10,10 +10,6 @@
 **
 ******************************************************************************
 **
-*/
-#if SQLITE_TEST          /* This file is used for testing only */
-
-/*
 ** This file contains the implementation of the Tcl [testvfs] command,
 ** used to create SQLite VFS implementations with various properties and
 ** instrumentation to support testing SQLite.
@@ -28,6 +24,7 @@
 **   -mxpathname INTEGER        (Value for sqlite3_vfs.mxPathname)
 **   -iversion   INTEGER        (Value for sqlite3_vfs.iVersion)
 */
+#if SQLITE_TEST          /* This file is used for testing only */
 
 #include "sqlite3.h"
 #include "sqliteInt.h"