usage map stuff

src/libmdb/data.c

@@ -21,6 +21,8 @@
 #include "time.h"
 #include "math.h"
 
+//#define FAST_READ 1
+
 char *mdb_money_to_string(MdbHandle *mdb, int start, char *s);
 static int _mdb_attempt_bind(MdbHandle *mdb, 
 	MdbColumn *col, unsigned char isnull, int offset, int len);
@@ -342,12 +344,34 @@ int mdb_read_next_dpg(MdbTableDef *table)
 MdbCatalogEntry *entry = table->entry;
 MdbHandle *mdb = entry->mdb;
 
+#if FAST_READ
+int pgnum, i, bitn;
+
+	pgnum = _mdb_get_int32(table->usage_map,1);
+	/* the first 5 bytes of the usage map mean something */
+	for (i=5;i<table->map_sz;i++) {
+		for (bitn=0;bitn<8;bitn++) {
+			if (table->usage_map[i] & 1 << bitn && pgnum > table->cur_phys_pg) {
+				table->cur_phys_pg = pgnum;
+				if (!mdb_read_pg(mdb, pgnum)) {
+					return 0;
+				} else {
+					return pgnum;
+				}
+			}
+			pgnum++;
+		}
+	}
+	/* didn't find anything */
+	return 0;
+#else
 	do {
 		if (!mdb_read_pg(mdb, table->cur_phys_pg++))
 			return 0;
 	} while (mdb->pg_buf[0]!=0x01 || mdb_get_int32(mdb, 4)!=entry->table_pg);
 	/* fprintf(stderr,"returning new page %ld\n", table->cur_phys_pg);  */
 	return table->cur_phys_pg;
+#endif
 }
 int mdb_rewind_table(MdbTableDef *table)
 {
@@ -418,6 +442,17 @@ int mdb_is_fixed_col(MdbColumn *col)
 {
 	return col->is_fixed;
 }
+static char *mdb_data_to_hex(MdbHandle *mdb, char *text, int start, int size) 
+{
+int i;
+
+	for (i=start; i<start+size; i++) {
+		sprintf(&text[(i-start)*2],"%02x", mdb->pg_buf[i]);
+	}
+	text[(i-start)*2]='\0';
+
+	return text;
+}
 static char *mdb_memo_to_string(MdbHandle *mdb, int start, int size)
 {
 guint16 memo_len;
@@ -577,6 +612,7 @@ char *mdb_col_to_string(MdbHandle *mdb, int start, int datatype, int size)
 {
 /* FIX ME -- not thread safe */
 static char text[MDB_BIND_SIZE];
+char tmpbuf[10];
 time_t t;
 int i,j;
 

src/libmdb/file.c

@@ -48,6 +48,7 @@ int j,pos;
 		mdb->tab_num_cols_offset = 45;
 		mdb->tab_num_idxs_offset = 47;
 		mdb->tab_num_ridxs_offset = 51;
+		mdb->tab_usage_map_offset = 55;
 		mdb->tab_first_dpg_offset = 56;
 		mdb->tab_cols_start_offset = 63;
 		mdb->tab_ridx_entry_size = 12;
@@ -62,6 +63,7 @@ int j,pos;
 		mdb->tab_num_cols_offset = 25;
 		mdb->tab_num_idxs_offset = 27;
 		mdb->tab_num_ridxs_offset = 31;
+		mdb->tab_usage_map_offset = 35;
 		mdb->tab_first_dpg_offset = 36;
 		mdb->tab_cols_start_offset = 43;
 		mdb->tab_ridx_entry_size = 8;
@@ -185,18 +187,26 @@ unsigned char *c;
 	mdb->cur_pos+=3;
 	return l;
 }
-long mdb_get_int32(MdbHandle *mdb, int offset)
+long _mdb_get_int32(unsigned char *buf, int offset)
 {
 long l;
 unsigned char *c;
 
-	if (offset <0 || offset+4 > mdb->pg_size) return -1;
-	c = &mdb->pg_buf[offset];
+	c = &buf[offset];
 	l =c[3]; l<<=8;
 	l+=c[2]; l<<=8;
 	l+=c[1]; l<<=8;
 	l+=c[0];
 
+	return l;
+}
+long mdb_get_int32(MdbHandle *mdb, int offset)
+{
+long l;
+
+	if (offset <0 || offset+4 > mdb->pg_size) return -1;
+
+	l = _mdb_get_int32(mdb->pg_buf, offset);
 	mdb->cur_pos+=4;
 	return l;
 }

src/libmdb/table.c

@@ -43,6 +43,7 @@ MdbTableDef *mdb_read_table(MdbCatalogEntry *entry)
 MdbTableDef *table;
 MdbHandle *mdb = entry->mdb;
 int len, i;
+int rownum, row_start, row_end;
 
 	table = mdb_alloc_tabledef(entry);
 
@@ -53,6 +54,22 @@ int len, i;
 	table->num_cols = mdb_get_int16(mdb, mdb->tab_num_cols_offset);
 	table->num_idxs = mdb_get_int32(mdb, mdb->tab_num_idxs_offset); 
 	table->num_real_idxs = mdb_get_int32(mdb, mdb->tab_num_ridxs_offset); 
+
+	/* grab a copy of the usage map */
+	rownum = mdb->pg_buf[mdb->tab_usage_map_offset];
+	mdb_read_alt_pg(mdb, mdb_get_int24(mdb, mdb->tab_usage_map_offset + 1)); 
+	mdb_swap_pgbuf(mdb);
+	row_start = mdb_get_int16(mdb, (mdb->row_count_offset + 2) + (rownum*2));
+   row_end = mdb_find_end_of_row(mdb, rownum);
+	table->map_sz = row_end - row_start;
+	table->usage_map = malloc(table->map_sz);
+	memcpy(table->usage_map, &mdb->pg_buf[row_start], table->map_sz);
+	buffer_dump(mdb->pg_buf, row_start, row_end);
+	/* swap back */
+	mdb_swap_pgbuf(mdb);
+	printf ("usage map found on page %ld start %d end %d\n", mdb_get_int24(mdb, mdb->tab_usage_map_offset + 1), row_start, row_end);
+
+
 	table->first_data_pg = mdb_get_int16(mdb, mdb->tab_first_dpg_offset);
 
 	return table;
@@ -208,7 +225,8 @@ MdbTableDef *table;
 MdbColumn *col;
 MdbIndex *idx;
 MdbHandle *mdb = entry->mdb;
-int i;
+int i,bitn;
+int pgnum;
 
 	table = mdb_read_table(entry);
 	fprintf(stdout,"definition page     = %d\n",entry->table_pg);
@@ -233,4 +251,15 @@ int i;
 		idx = g_ptr_array_index (table->indices, i);
 		mdb_index_dump(table, idx);
 	}
+	if (table->usage_map) {
+		pgnum = _mdb_get_int32(table->usage_map,1);
+		/* the first 5 bytes of the usage map mean something */
+		for (i=5;i<table->map_sz;i++) {
+			for (bitn=0;bitn<8;bitn++) {
+				if (table->usage_map[i] & 1 << bitn) 
+					printf("page %ld is reserved by this object\n",pgnum);
+				pgnum++;
+			}
+		}
+	}
 }