--- /dev/null
+/*
+ * Copyright (C) 1994, Index Data I/S
+ * All rights reserved.
+ * Sebastian Hammer, Adam Dickmeiss
+ *
+ * $Log: memory.c,v $
+ * Revision 1.1 1994-09-26 16:07:56 quinn
+ * Most of the functionality in place.
+ *
+ */
+
+/*
+ * This module accesses and rearranges the records of the tables.
+ */
+
+#include <assert.h>
+
+#include <util.h>
+#include "memory.h"
+#include "physical.h"
+#include <isam.h>
+
+int is_mbuf_size[3] = { 0, 1024, 4096 };
+
+/*
+ * TODO: make internal memory-management scheme for these units.
+ */
+
+is_mblock *xmalloc_mblock()
+{
+ is_mblock *tmp;
+
+ tmp = xmalloc(sizeof(is_mblock));
+ tmp->next = 0;
+ return tmp;
+}
+
+is_mbuf *xmalloc_mbuf(int type)
+{
+ is_mbuf *tmp;
+
+ tmp = xmalloc(sizeof(is_mbuf) + is_mbuf_size[type]);
+ tmp->type = type;
+ tmp->refcount = type ? 1 : 0;
+ tmp->offset = tmp->num = tmp->cur_record = 0;
+ tmp->data = (char*) tmp + sizeof(is_mbuf);
+ tmp->next = 0;
+ return tmp;
+}
+
+#if 0
+void xfree_mblock(is_mblock *p)
+{
+ xfree(p);
+}
+#endif
+
+#if 0
+void xfree_mbuf(is_mblock *p)
+{
+ xfree(p);
+}
+#endif
+
+void is_m_establish_tab(ISAM is, is_mtable *tab, ISAM_P pos)
+{
+ tab->data = xmalloc_mblock();
+ if (pos > 0)
+ {
+ tab->pos_type = is_type(pos);
+ tab->num_records = -1;
+ tab->data->num_records = -1;
+ tab->data->diskpos = is_block(pos);
+ tab->data->state = IS_MBSTATE_UNREAD;
+ tab->data->data = 0;
+ tab->cur_mblock = tab->data;
+ tab->cur_mblock->cur_mbuf = 0;
+ }
+ else /* new block */
+ {
+ tab->pos_type = 0;
+ tab->num_records = 0;
+ tab->data->num_records = 0;
+ tab->data->diskpos = -1;
+ tab->data->state = IS_MBSTATE_CLEAN;
+ tab->data->data = xmalloc_mbuf(IS_MBUF_TYPE_LARGE);
+ tab->cur_mblock = tab->data;
+ tab->cur_mblock->cur_mbuf = tab->data->data;
+ tab->cur_mblock->cur_mbuf->cur_record = 0;
+ }
+ tab->is = is;
+}
+
+void is_m_rewind(is_mtable *tab)
+{
+ tab->cur_mblock = tab->data;
+ if (tab->data)
+ {
+ tab->data->cur_mbuf = tab->data->data;
+ if (tab->data->data)
+ tab->data->data->cur_record = 0;
+ }
+}
+
+static int read_current_full(is_mtable *tab, is_mblock *mblock)
+{
+ if (is_p_read_full(tab, mblock) < 0)
+ return -1;
+ if (mblock->nextpos && !mblock->next)
+ {
+ mblock->next = xmalloc_mblock();
+ mblock->next->diskpos = mblock->nextpos;
+ mblock->next->state = IS_MBSTATE_UNREAD;
+ mblock->next->data = 0;
+ }
+ mblock->cur_mbuf = mblock->data;
+ mblock->data->cur_record = 0;
+ return 0;
+}
+
+int is_m_read_full(is_mtable *tab, is_mblock *mblock)
+{
+ return read_current_full(tab, mblock);
+}
+
+/*
+ * replace the record right behind the pointer.
+ */
+void is_m_replace_record(is_mtable *tab, const void *rec)
+{
+ is_mbuf *mbuf = tab->cur_mblock->cur_mbuf;
+
+ /* we assume that block is already in memory and that we are in the
+ * right mbuf, and that it has space for us. */
+ memcpy(mbuf->data + mbuf->offset + (mbuf->cur_record - 1) *
+ is_keysize(tab->is), rec, is_keysize(tab->is));
+ tab->cur_mblock->state = IS_MBSTATE_DIRTY;
+}
+
+/*
+ * Delete the record right behind the pointer.
+ */
+void is_m_delete_record(is_mtable *tab)
+{
+ is_mbuf *mbuf, *new;
+
+ mbuf = tab->cur_mblock->cur_mbuf;
+ if (mbuf->cur_record >= mbuf->num) /* top of mbuf */
+ {
+ mbuf->num--;
+ mbuf->cur_record--;
+ }
+ else /* middle of a block */
+ {
+ new = xmalloc_mbuf(IS_MBUF_TYPE_SMALL);
+ new->next = mbuf->next;
+ mbuf->next = new;
+ new->data = mbuf->data;
+ mbuf->refcount++;
+ new->offset = mbuf->offset + mbuf->cur_record * is_keysize(tab->is);
+ new->num = mbuf->num - mbuf->cur_record;
+ mbuf->num = mbuf->cur_record -1;
+ mbuf = mbuf->next;
+ mbuf->cur_record = 0;
+ }
+ tab->num_records--;
+ tab->cur_mblock->num_records--;
+ tab->cur_mblock->state = tab->data->state = IS_MBSTATE_DIRTY;
+}
+
+int is_m_write_record(is_mtable *tab, const void *rec)
+{
+ is_mbuf *mbuf, *oldnext, *dmbuf;
+
+ /* make sure block is all in memory */
+ if (tab->cur_mblock->state <= IS_MBSTATE_PARTIAL)
+ if (read_current_full(tab, tab->cur_mblock) < 0)
+ return -1;
+ mbuf = tab->cur_mblock->cur_mbuf;
+ if (mbuf->cur_record >= mbuf->num) /* top of mbuf */
+ {
+ /* mbuf is reference or full */
+ if (mbuf->refcount != 1 || mbuf->offset + (mbuf->num + 1) *
+ is_keysize(tab->is) > is_mbuf_size[mbuf->type])
+ {
+ oldnext = mbuf->next;
+ mbuf->next = xmalloc_mbuf(IS_MBUF_TYPE_LARGE);
+ mbuf->next->next = oldnext;
+ mbuf = mbuf->next;
+ tab->cur_mblock->cur_mbuf = mbuf;
+ mbuf->cur_record = 0;
+ }
+ }
+ else
+ {
+ oldnext = mbuf->next;
+ mbuf->next = xmalloc_mbuf(IS_MBUF_TYPE_MEDIUM);
+ mbuf->next->next = dmbuf = xmalloc_mbuf(IS_MBUF_TYPE_SMALL);
+ dmbuf->data = mbuf->data;
+ dmbuf->next = oldnext;
+ dmbuf->offset = mbuf->offset + mbuf->cur_record * is_keysize(tab->is);
+ dmbuf->num = mbuf->num - mbuf->cur_record;
+ mbuf->num -= dmbuf->num;
+ mbuf->refcount++;
+ mbuf = tab->cur_mblock->cur_mbuf = mbuf->next;
+ mbuf->cur_record = 0;
+ }
+ log(LOG_DEBUG, "is_m_write_rec(rec == %d)", mbuf->cur_record);
+ memcpy(mbuf->data + mbuf->offset + mbuf->cur_record * is_keysize(tab->is),
+ rec, is_keysize(tab->is));
+ mbuf->num++;
+ mbuf->cur_record++;
+ tab->num_records++;
+ tab->cur_mblock->num_records++;
+ tab->cur_mblock->state = tab->data->state = IS_MBSTATE_DIRTY;
+ return 0;
+}
+
+void is_m_unread_record(is_mtable *tab)
+{
+ assert(tab->cur_mblock->cur_mbuf->cur_record);
+ tab->cur_mblock->cur_mbuf->cur_record--;
+}
+
+/*
+ * non-destructive read.
+ */
+int is_m_peek_record(is_mtable *tab, void *rec)
+{
+ is_mbuf *mbuf;
+
+ /* make sure block is all in memory */
+ if (tab->cur_mblock->state <= IS_MBSTATE_PARTIAL)
+ if (read_current_full(tab, tab->cur_mblock) < 0)
+ return -1;
+ mbuf = tab->cur_mblock->cur_mbuf;
+ if (mbuf->cur_record >= mbuf->num) /* are we at end of mbuf? */
+ {
+ if (!mbuf->next) /* end of mblock */
+ {
+ if (tab->cur_mblock->next)
+ {
+ tab->cur_mblock = tab->cur_mblock->next;
+ if (tab->cur_mblock->next->state <= IS_MBSTATE_PARTIAL)
+ if (read_current_full(tab, tab->cur_mblock->next) < 0)
+ return -1;
+ mbuf = tab->cur_mblock->next->data;
+ }
+ else
+ return 0; /* EOTable */
+ }
+ else
+ mbuf = mbuf->next;
+ mbuf->cur_record = 0;
+ }
+ memcpy(rec, mbuf->data + mbuf->offset + mbuf->cur_record *
+ is_keysize(tab->is), is_keysize(tab->is));
+ return 1;
+}
+
+int is_m_read_record(is_mtable *tab, void *buf)
+{
+ is_mbuf *mbuf;
+
+ /* make sure block is all in memory */
+ if (tab->cur_mblock->state <= IS_MBSTATE_PARTIAL)
+ if (read_current_full(tab, tab->cur_mblock) < 0)
+ return -1;
+ mbuf = tab->cur_mblock->cur_mbuf;
+ if (mbuf->cur_record >= mbuf->num) /* are we at end of mbuf? */
+ {
+ if (!mbuf->next) /* end of mblock */
+ {
+ if (tab->cur_mblock->next)
+ {
+ tab->cur_mblock = tab->cur_mblock->next;
+ if (tab->cur_mblock->state <= IS_MBSTATE_PARTIAL)
+ if (read_current_full(tab, tab->cur_mblock) < 0)
+ return -1;
+ tab->cur_mblock->cur_mbuf = mbuf = tab->cur_mblock->data;
+ }
+ else
+ return 0; /* EOTable */
+ }
+ else
+ tab->cur_mblock->cur_mbuf = mbuf = mbuf->next;
+ mbuf->cur_record = 0;
+ }
+ memcpy(buf, mbuf->data + mbuf->offset + mbuf->cur_record *
+ is_keysize(tab->is), is_keysize(tab->is));
+ mbuf->cur_record++;
+ return 1;
+}
+
+/*
+ * TODO: optimize this function by introducing a higher-level search.
+ */
+int is_m_seek_record(is_mtable *tab, const void *rec)
+{
+ char peek[IS_MAX_RECORD];
+ int rs;
+
+ for (;;)
+ {
+ if (is_m_read_record(tab, &peek) <= 0)
+ return 1;
+ if ((rs = (*tab->is->cmp)(peek, rec)) > 0)
+ {
+ is_m_unread_record(tab);
+ return 1;
+ }
+ else if (rs == 0)
+ return 0;
+ }
+}
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