X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcode%2Fhash-table.lisp;h=9f2a6b4325773ef5dad0e4f87d73c382a71c5268;hb=dcb73f3edef1e31078fbe585e2fafbd26743efd7;hp=d8f5e136353f06f674eb0556eb65c5f771175ed9;hpb=bc1783335d78be988465e4fc7cf9c5fdb88a3fa4;p=sbcl.git

diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp
index d8f5e13..9f2a6b4 100644
--- a/src/code/hash-table.lisp
+++ b/src/code/hash-table.lisp
@@ -39,11 +39,13 @@
   (number-entries 0 :type index)
   ;; The Key-Value pair vector.
   (table (missing-arg) :type simple-vector)
-  ;; True if this is a weak hash table, meaning that key->value
-  ;; mappings will disappear if there are no other references to the
-  ;; key. Note: this only matters if the hash function indicates that
-  ;; the hashing is EQ based.
-  (weak-p nil :type (member t nil))
+  ;; This slot is used to link weak hash tables during GC. When the GC
+  ;; isn't running it is always NIL.
+  (next-weak-hash-table nil :type null)
+  ;; Non-NIL if this is some kind of weak hash table. For details see
+  ;; the docstring of MAKE-HASH-TABLE.
+  (weakness nil :type (member nil :key :value :key-or-value :key-and-value)
+            :read-only t)
   ;; Index into the next-vector, chaining together buckets that need
   ;; to be rehashed because their hashing is EQ based and the key has
   ;; been moved by the garbage collector.
@@ -66,10 +68,22 @@
   ;; This table parallels the KV table, and can be used to store the
   ;; hash associated with the key, saving recalculation. Could be
   ;; useful for EQL, and EQUAL hash tables. This table is not needed
-  ;; for EQ hash tables, and when present the value of #x80000000
-  ;; represents EQ-based hashing on the respective key.
+  ;; for EQ hash tables, and when present the value of
+  ;; +MAGIC-HASH-VECTOR-VALUE+ represents EQ-based hashing on the
+  ;; respective key.
   (hash-vector nil :type (or null (simple-array (unsigned-byte
-                                                 #.sb!vm:n-word-bits) (*)))))
+                                                 #.sb!vm:n-word-bits) (*))))
+  ;; This lock is acquired by %PUTHASH, REMHASH, CLRHASH and GETHASH.
+  (spinlock (sb!thread::make-spinlock)))
+
+;; as explained by pmai on openprojects #lisp IRC 2002-07-30: #x80000000
+;; is bigger than any possible nonEQ hash value, and thus indicates an
+;; empty slot; and EQ hash tables don't use HASH-TABLE-HASH-VECTOR.
+;; The previous sentence was written when SBCL was 32-bit only. The value
+;; now depends on the word size. It is propagated to C in genesis because
+;; the generational garbage collector needs to know it.
+(defconstant +magic-hash-vector-value+ (ash 1 (1- sb!vm:n-word-bits)))
+
 
 (defmacro-mundanely with-hash-table-iterator ((function hash-table) &body body)
   #!+sb-doc