mal_box.mx

一个内存数据库的源代码这是服务器端还有客户端

		if (idcmp(box[j]->name, name) == 0) {
			free(box[i]->name);
			freeMalBlk(box[i]->sym);
			freeStack(box[i]->val);
			boxfile = boxFileName(box[i], 0);
			unlink(boxfile);
			GDKfree(boxfile);
			MT_destroy_lock(box[i]->lock);
		} else
			box[i] = box[j++];
	}
	mal_unset_lock(mal_contextLock, "destroyBox");

}

@- Operations
The deposit operation silently accepts any request to store
an element.
@c
int
depositBox(Box box, str name, ValPtr val)
{
	int i;
	ValPtr v;

	i = findVariable(box->sym, name);
	if (i < 0) {
		i = newVariable(box->sym, GDKstrdup(name), val->vtype);
		chkStack(box->val, i);
	}
	v = &box->val->stk[i];
	box->val->stktop++;
	VALcopy(v, val);
	box->dirty= TRUE;
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "depositBox: entered '%s' at %d type %d\n", name, i, v->vtype);
#endif
	return 0;
}

void
insertToBox(Box box, str nme, str val)
{
	ValRecord vr;

	vr.vtype = TYPE_str;
	vr.val.sval = val? val: (str)str_nil;
	vr.len = strlen(vr.val.sval);
	depositBox(box, nme, &vr);
}

@-
Taking an element from a box is only permitted if the type of
the receiver matches the type of the source.
@c
int
takeBox(Box box, str name, ValPtr val, int tpe)
{
	int i;
	ValPtr v;

	i = findVariable(box->sym, name);
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "takeBox: found '%s' at %d\n", name, i);
#endif
	if (i < 0)
		return i;
	v = &box->val->stk[i];
	if (val->vtype != v->vtype && v->vtype != TYPE_any && tpe != TYPE_any) {
#ifdef DEBUG_MAL_BOX
		stream_printf(GDKout, "takeBox:type error %d,%d\n", val->vtype, box->val->stk[i].vtype);
#endif
		return -1;
	}
	VALcopy(val, &box->val->stk[i]);
	if (val->vtype == TYPE_bat)
		BBPincref(val->val.br.id, TRUE);

#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "takeBox:'%s' from '%s'\n", name, box->name);
#endif
	return 0;
}

@-
The function bindBAT relates a logical BAT name with a physical
representation. The bind commands are typically found in the boxes,
which provide users a partial view over the BAT storage area.
That is, all bats bound can be taken out of the box upon need.
A variable can be rebound to another BAT at any time.
@c
int
bindBAT(Box box, str name, str location)
{
	int i;
	ValPtr v;

	i = findVariable(box->sym, name);
	if (i < 0)
		i = newVariable(box->sym, GDKstrdup(name), TYPE_any);
	v = &box->val->stk[i];
	v->val.br.id = BBPindex(location);

	if (v->val.br.id == 0)
		return -1;
	v->vtype = TYPE_bat;
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "bindBox:'%s' to '%s' [%d] in '%s'\n", name, location, v->val.br.id, box->name);
#endif
	return 0;
}

int
releaseBox(Box box, str name)
{
	int i;

#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "releaseBox:%s from %s\n", name, box->name);
#endif
	i = findVariable(box->sym, name);
	if (i < 0)
		return i;
	return 0;
}

int
releaseAllBox(Box box)
{
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "releaseAllBox:%s \n", box->name);
#else
	(void) box;
#endif
	return 0;
}

int
discardBox(Box box, str name)
{
	int i, j;

#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "discardBox:%s from %s\n", name, box->name);
#endif
	i = findVariable(box->sym, name);
	if (i < 0)
		return i;
	garbageElement(&box->val->stk[i]);
	for (j = i; j < box->sym->vtop - 2; j++) {
		box->sym->var[j] = box->sym->var[j + 1];

		VALcopy(&box->val->stk[j], &box->val->stk[j + 1]);
	}
	box->sym->vtop--;
	box->val->stktop--;
	box->dirty= TRUE;
	return 0;
}

@-
The elements can be obtained using iterator, which returns the name
of the next element in the box.
@c
int
nextBoxElement(Box box, lng *cursor, ValPtr v)
{
	if (*cursor >= box->sym->vtop) {
		*cursor = -1;
		return 0;
	}
	v->vtype = TYPE_str;
	v->val.pval = getBoxName(box, *cursor);
	*cursor = *cursor + 1;
	return 0;
}

str
getBoxName(Box box, lng i)
{
	str s;

	s = getVarName(box->sym, (int) i);
	return GDKstrdup(s);
}

str
toString(Box box, lng i)
{
	(void) box;
	(void) i;		/* fool the compiler */
	return GDKstrdup("");
}

str
getBoxNames(int *bid)
{
	BAT *b;
	int i;

	b = BATnew(TYPE_int, TYPE_str, (size_t) MAXSPACES);
	for (i = 0; i < MAXSPACES; i++)
		if (box[i] != NULL) {
			BUNins(b, &i, box[i]->name, FALSE);
		}
	BBPincref(*bid = b->batCacheid, TRUE);
	BBPunfix(*bid);
	return MAL_SUCCEED;
}

@- Persistency
The content of a box is saved on a file for subsequent re-use.
The storage is explicitly in terms of MAL operations.
For BAT objects, the corresponding object is made persistent.
Note that the user can not control these operations directly.
The box container is created if it did not yet exist.
@c
str
boxFileName(Box box, str backup)
{
	char boxfile[PATHLENGTH];
	size_t i = 0;

	snprintf(boxfile, PATHLENGTH, "%s%c%s%cbox", GDKgetenv("gdk_dbfarm"), DIR_SEP, GDKgetenv("gdk_dbname"), DIR_SEP);
	if (mkdir(boxfile, 0755) < 0 && errno != EEXIST) {
		showException(MAL,"box.fileName", "can not create box directory");
		return NULL;
	}
	i = strlen(boxfile);
	if (backup) {
		snprintf(boxfile + i, PATHLENGTH - i, "%c%s", DIR_SEP, backup);
		if (mkdir(boxfile, 0755) < 0 && errno != EEXIST) {
			showException(MAL,"box.fileName", "can not create box directory");
			return NULL;
		}
		i += strlen(backup) + 1;
	}
	snprintf(boxfile + i, PATHLENGTH - i, "%c%s.box", DIR_SEP, box->name);
	return GDKstrdup(boxfile);
}

#ifndef R_OK
#define R_OK 4
#endif
stream *
prepareSaveBox(Box box, str *boxfile, str *boxfilebak)
{
	stream *f;

	*boxfile = boxFileName(box, 0);
	*boxfilebak = boxFileName(box, "backup");

	if (*boxfile == 0) {
		showException(MAL, "box.saveBox", "can not determine box file");
		return 0;
	}
	if (access(*boxfile,R_OK)==0 && rename(*boxfile, *boxfilebak)) {
#ifdef DEBUG_MAL_BOX
		stream_printf(GDKout, "saveBox:can not rename %s\n", boxfile);
#endif
		showException(MAL,"box.saveBox", "can not rename backup");
		GDKfree(*boxfile); *boxfile = NULL;
		GDKfree(*boxfilebak); *boxfilebak = NULL;
		return 0;
		}

	f = open_wastream(*boxfile);
#ifndef S_IRUSR
#define S_IRUSR 0400
#define S_IWUSR 0200
#endif
	if (f != NULL)
		chmod(*boxfile, (S_IRUSR | S_IWUSR));
	else
		showException(MAL,"box.saveBox", "can not create box file");
	if (f == NULL) {
		GDKfree(*boxfile); *boxfile= NULL;
		GDKfree(*boxfilebak); *boxfilebak= NULL;
	}
	return f;
}

int
saveBox(Box box, int flag)
{
	int i;
	stream *f;
	ValPtr v;
	str boxfile, boxfilebak;

	(void) flag;		/* fool the compiler */

	if( box->dirty== FALSE)
		return 0;
	f = prepareSaveBox(box, &boxfile, &boxfilebak);
	if (f == NULL)
		return 1;
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "saveBox:created %s\n", boxfile);
#endif
	for (i = 0; i < box->sym->vtop; i++) {
		v = &box->val->stk[i];
		if (v->vtype == TYPE_bat) {
			BAT *b = (BAT *) BBPgetdesc(v->val.br.id);

			if (b && b->batPersistence & PERSISTENT){
				stream_printf(f, "%s.bind(\"%s\",\"%s\");\n", 
					box->name, getVarName(box->sym, i), 
					BBPname(v->val.br.id));
				BATcommit(b);
			}
		} else {
			stream_printf(f, "%s := ", getVarName(box->sym, i));
			ATOMprint(v->vtype, VALptr(v), f);
			stream_printf(f, ":%s;\n", getTypeName(v->vtype));
			stream_printf(f, "%s.deposit(\"%s\",%s);\n", 
				box->name, getVarName(box->sym, i), getVarName(box->sym, i));
		}
	}
	close_stream(f);
	GDKfree(boxfile);
	GDKfree(boxfilebak);
	return 0;
}

@-
Loading a box is equivalent to reading a script.
Beware to execute it into its own context.
@c
void
loadBox(str name)
{
	char boxfile[PATHLENGTH];
	size_t i = 0;

	snprintf(boxfile, PATHLENGTH, "%s%c%s%cbox", GDKgetenv("gdk_dbfarm"), DIR_SEP, GDKgetenv("gdk_dbname"), DIR_SEP);
	mkdir(boxfile,0755); /* ignore errors */
	i = strlen(boxfile);
	snprintf(boxfile + i, PATHLENGTH - i, "%c%s.box", DIR_SEP, name);
#ifdef DEBUG_MAL_BOX
	stream_printf(GDKout, "loadBox:start loading the file %s\n", boxfile);
#endif
	if (access(boxfile, R_OK) == 0) {
		Client child= MCforkClient(MCgetClient());
		defaultScenario(child);
		evalFile(child, boxfile, 0);
		MCkillClient(child,2);
#ifdef DEBUG_MAL_BOX
		stream_printf(GDKout, "loadBox:loaded the file %s\n", boxfile);
#endif
	}
}

@- Utilities
Utilities for the debugger permit dumping of all the object
spaces.
@c
void
printBox(stream *fd, Box obj)
{
	printStack(fd, obj->sym, obj->val,0);
}

void
printSomeBox(stream *fd, int k)
{
	if (box[k] == 0) {
		showException(MAL,"box.printSomeBox", "illegal space id: %d", k);
	} else
		printBox(fd, box[k]);
}

@}