shithub: asif

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zalloc: keep track of used nodes and add reaping them all at once

--- a/asif.h

+++ b/asif.h

@@ -107,6 +107,7 @@

 	usize elsize;

 	void data[];

 };

+void	znuke(Zpool*);

 void	zfree(void*);

 void*	zalloc(Zpool*);

 Zpool*	znew(usize);

--- a/zalloc.c

+++ b/zalloc.c

@@ -2,9 +2,11 @@

 #include <libc.h>

 #include "asif.h"

-/* no nodes are ever freed, left to be reclaimed by the kernel on exit

- * got more complicated, but should be able to detect some bugs...

- * unsuitable for very large collections probably */

+/* "simple" "slab allocation" free lists: no memory is ever freed, left to be

+ * reclaimed by the kernel on exit; should be able to detect some bugs, but

+ * still convoluted. keeps track of used nodes to be able to reap them all at

+ * once.

+ */

 typedef struct Zhouse Zhouse;

 typedef struct Znode Znode;

@@ -24,6 +26,7 @@

 };

 struct Zhouse{

 	Zpool;

+	Znode used;

 	Znode;

 };

@@ -58,15 +61,34 @@

 }

 static void

-zlink(Znode *p, Zhouse *z)

+zlink(Znode *p, Znode *l, int clr)

 {

-	zcheckpool(p, z);

-	p->prev = z->prev;

-	p->next = &z->Znode;

-	z->prev->next = p;

-	z->prev = p;

+	if(clr){

+		p->next->prev = p->prev;

+		p->prev->next = p->next;

+	}

+	p->prev = l->prev;

+	p->next = l;

+	l->prev->next = p;

+	l->prev = p;

 }

+void

+znuke(Zpool *zp)

+{

+	Zhouse *z;

+

+	if(zp == nil)

+		return;

+	z = (Zhouse *)zp;

+	/* prev → z → NEXT → … → PREV → next; contents must be zeroed */

+	z->used.prev->next = z->next;

+	z->next->prev = z->used.prev;

+	z->next = z->used.next;

+	z->used.next->prev = &z->Znode;

+	z->used.next = z->used.prev = &z->used;

+}

+

 static Znode *

 zpop(Zhouse *z)

 {

@@ -74,10 +96,7 @@

 	p = z->next;

 	assert(p != z);

-	zcheckpool(p, z);

-	p->next->prev = &z->Znode;

-	z->next = p->next;

-	p->prev = p->next = nil;

+	zlink(p, &z->used, 1);

 	return p;

 }

@@ -91,7 +110,7 @@

 	z = p->z;

 	zcheckpool(p, z);

 	memset(p->data, 0, z->elsize);

-	zlink(p, z);

+	zlink(p, &z->Znode, 1);

 }

 void

@@ -120,7 +139,7 @@

 		p->z = z;

 		t = n2t(p);

 		t->z = z;

-		zlink(p, z);

+		zlink(p, &z->Znode, 0);

 	}

 }

@@ -133,6 +152,7 @@

 	z = (Zhouse *)zp;

 	zfeed(z);

 	p = zpop(z);

+	memset(p->data, 0, z->elsize);

 	return p->data;

 }

@@ -145,6 +165,7 @@

 	z = emalloc(sizeof *z);

 	z->elsize = elsize;

 	z->next = z->prev = z;

+	z->used.next = z->used.prev = &z->used;

 	zfeed(z);

 	return z;

 }