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/*
* Copyright 1995,96 Thierry Bousch
* Licensed under the Gnu Public License, Version 2
*
* $Id: memoize.c,v 2.6 1996/09/18 10:02:56 bousch Exp $
*
* Memoization of worthwhile objects. This requires the gdbm(3) library.
*/
#include <assert.h>
#include <errno.h>
#include <gdbm.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "saml.h"
#include "saml-parse.h"
#include "induce.h"
typedef struct _memo_entry {
struct _memo_entry *next;
int arity;
const char* rootname;
int slot;
} PRECIOUS_ENTRY;
typedef struct {
const char *filename;
GDBM_FILE handle;
} DB_ENTRY;
#define MAX_DB_ENTRIES 30
static DB_ENTRY db_entries[MAX_DB_ENTRIES];
static int nb_db_entries = 0, current_db_entry = -1;
static char temporary_memo[] = _PATH_TMPMEMO;
static PRECIOUS_ENTRY *precious_list[256];
int register_memo (const char *filename)
{
GDBM_FILE gf;
int i;
filename = tilde_expand(filename);
/* Already registered ? */
for (i = 0; i < nb_db_entries; i++)
if (strcmp(db_entries[i].filename,filename) == 0)
return (current_db_entry = i);
if (nb_db_entries >= MAX_DB_ENTRIES-1) {
fprintf(stderr,
"induce: too many memos (max %d), skipping `%s'\n",
MAX_DB_ENTRIES, filename);
return (current_db_entry = -1);
}
if (strcmp(filename,"-") == 0) {
mktemp(temporary_memo);
gf = gdbm_open(temporary_memo, 0, GDBM_WRCREAT|GDBM_FAST,
0666, NULL);
if (gf == NULL)
perror("induce: gdbm_open");
unlink(temporary_memo);
} else {
/* The prototype of gdbm_open() ought to be fixed, really */
gf = gdbm_open(filename, 0, GDBM_WRCREAT, 0666, NULL);
if (gf == NULL)
perror("induce: gdbm_open");
}
current_db_entry = -1;
if (gf) {
current_db_entry = nb_db_entries++;
db_entries[current_db_entry].filename = filename;
db_entries[current_db_entry].handle = gf;
}
return current_db_entry;
}
static inline int hash (const char *rootname, int arity)
{
/*
* Takes two bits from the arity, six from rootname[0], and
* thus returns a number in [0..255].
*/
return (*rootname & 63) | ((arity & 3) << 6);
}
static int get_memo2 (const char* rootname, int arity)
{
PRECIOUS_ENTRY *p;
int h = hash(rootname, arity);
for (p = precious_list[h]; p; p = p->next)
if (p->arity == arity && !strcmp(p->rootname,rootname))
return p->slot;
return -1;
}
static GDBM_FILE get_memo (const char *name)
{
char *rootname, c, *p;
int arity, slot;
rootname = alloca(strlen(name) + 1);
strcpy(rootname, name);
arity = 0;
p = strchr(rootname, '[');
if (p != NULL) {
arity = 1;
*p++ = '\0'; /* Isolate the rootname */
while ((c = *p++) != '\0')
if (c == ',')
++arity;
}
slot = get_memo2(rootname, arity);
if (slot < 0)
return NULL;
return db_entries[slot].handle;
}
void declare_precious (const char *rootname, int arity)
{
int h;
PRECIOUS_ENTRY *p;
if (floating_precision || current_db_entry < 0) {
/* Memoizing is disabled. */
return;
}
if (get_memo2(rootname, arity) >= 0) {
/* Already declared as precious */
return;
}
h = hash(rootname, arity);
p = malloc(sizeof(PRECIOUS_ENTRY)); assert(p);
p->next = precious_list[h];
precious_list[h] = p;
p->arity = arity;
p->rootname = rootname;
p->slot = current_db_entry;
}
int is_saved (const char* name)
{
datum key;
GDBM_FILE memo = get_memo(name);
if (!memo)
return 0;
key.dptr = (char *) name;
key.dsize = strlen(key.dptr);
return gdbm_exists(memo, key);
}
int save_precious (vertex *v)
{
datum key, content;
GDBM_FILE memo = get_memo(v->name);
int ret;
if (!memo)
return -1; /* not precious */
key.dptr = v->name;
key.dsize = strlen(key.dptr);
content.dptr = mref_string(v->mr);
content.dsize = strlen(content.dptr);
ret = gdbm_store(memo, key, content, GDBM_REPLACE);
if (ret != 0)
fprintf(stderr, "save_precious: store failed\n");
return ret;
}
int retrieve_precious (vertex *v)
{
datum key, content;
GDBM_FILE memo = get_memo(v->name);
mref_t model;
int ret;
if (!memo)
return -1; /* not precious */
key.dptr = v->name;
key.dsize = strlen(key.dptr);
content = gdbm_fetch(memo, key);
if (content.dptr == NULL) {
/* Record not found */
return -1;
}
#if 0
ret = parse_poly(v->mr, ST_RATIONAL, content.dptr, content.dsize);
#else
model = mref_new();
mref_build(model, ST_RATIONAL, "0");
mref_cast(model, parsed_poly_type);
saml_init_lexer_mem(content.dptr, content.dsize);
ret = saml_parse(v->mr, model);
mref_free(model);
#endif
/* Gdbm does not free this space itself */
free(content.dptr);
if (ret != 0) {
fprintf(stderr, "retrieve_precious(%s): syntax error\n",
v->name);
return -1;
}
return 0;
}
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