Improve memory mapping support.

The new code is more flexible and performs better when
lots of inserts are being made (e.g. when populating the
database with new data).

* src/gdbm.h.in (GDBM_SETMAXMAPSIZE): New constant.
* src/gdbmconst.h (SIZE_T_MAX): New define.
* src/gdbmdefs.h (gdbm_file_info) <cache_size>: Change type
to size_t.
<mmap_inited,mapped_size_max>: New member.
<mapped_remap>: Remove.
* src/gdbmopen.c: Fix a typo.
(gdbm_open): Initialize new members.
(_gdbm_init_cache): Second argument is size_t.
* src/gdbmsetopt.c (gdbm_setopt): Optval argument is void*.
Handle GDBM_SETMAXMAPSIZE.
Improve error checking.
* src/mmap.c (_GDBM_IN_MAPPED_REGION_P): Fix comparison with
the lower bound.
(_GDBM_NEED_REMAP): Return true if mapped_region is NULL.
(SUM_FILE_SIZE): Rewrite.
(_gdbm_mapped_unmap): Don't call msync.
(_gdbm_internal_remap): Take 2 arguments, the second one
giving the new mapped size.
Unmap the region prior to remapping it.
Always pass NULL as the argument to mmap.
(_gdbm_mapped_remap): Rewrite the logic. Change semantics of the
third argument. All uses updated.
(_gdbm_mapped_init): Reflect the above changes.
(_gdbm_mapped_read,_gdbm_mapped_write): Use mmap_inited to decide
whether to use mmap, because mapped_region can be reset to zero
by another functions (namely, _gdbm_mapped_lseek).
Reset mmap_inited to FALSE, if _gdbm_mapped_remap fails.
(_gdbm_mapped_lseek): Rewrite offset computations. Invalidate
the mapped region.
* src/proto.h (_gdbm_init_cache): Change prototype.
* src/update.c (write_header, _gdbm_end_update): Remove checks
for dbf->mapped_region.
* tests/gtload.c: Implement the -maxmap option (set maximal
mapped memory size).

* doc/gdbm.texinfo: Document GDBM_SETMAXMAPSIZE.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/gdbm.h.in b/src/gdbm.h.in
index 70de4e0..8eaee79 100644
--- a/src/gdbm.h.in
+++ b/src/gdbm.h.in
@@ -51,6 +51,7 @@
 #define GDBM_SYNCMODE	3	/* Turn on or off sync operations. */
 #define GDBM_CENTFREE	4	/* Keep all free blocks in the header. */
 #define GDBM_COALESCEBLKS 5	/* Attempt to coalesce free blocks. */
+#define GDBM_SETMAXMAPSIZE 6    /* Set maximum mapped memory size */
 
 /* The data and key structure. */
 typedef struct {
@@ -89,7 +90,7 @@ extern datum gdbm_nextkey (GDBM_FILE, datum);
 extern int gdbm_reorganize (GDBM_FILE);
 extern void gdbm_sync (GDBM_FILE);
 extern int gdbm_exists (GDBM_FILE, datum);
-extern int gdbm_setopt (GDBM_FILE, int, int *, int);
+extern int gdbm_setopt (GDBM_FILE, int, void *, int);
 extern int gdbm_fdesc (GDBM_FILE);
 extern int gdbm_export (GDBM_FILE, const char *, int, int);
 extern int gdbm_import (GDBM_FILE, const char *, int);
@@ -136,6 +137,7 @@ extern "C" {
 #endif
 
 extern const char *gdbm_strerror (gdbm_error);
+extern int gdbm_version_cmp (int const a[], int const b[]);
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }