X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fhash-table.lisp;h=22740e516dbd8b69d4e2d82f29b8a9aec372b625;hb=fd324a9d981355d8bc10d2bd469cb54c4c9108fd;hp=db58433533749a7118ae6249a9e403a80c13a84e;hpb=4898ef32c639b1c7f4ee13a5ba566ce6debd03e6;p=sbcl.git

diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp
index db58433..22740e5 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.
@@ -51,6 +53,9 @@
   ;; Index into the Next vector chaining together free slots in the KV
   ;; vector.
   (next-free-kv 0 :type index)
+  ;; A cache that is either nil or is an index into the hash table
+  ;; that should be checked first
+  (cache nil :type (or null index))
   ;; The index vector. This may be larger than the hash size to help
   ;; reduce collisions.
   (index-vector (missing-arg)
@@ -63,25 +68,40 @@
   ;; 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
   "WITH-HASH-TABLE-ITERATOR ((function hash-table) &body body)
-   provides a method of manually looping over the elements of a hash-table.
-   FUNCTION is bound to a generator-macro that, within the scope of the
-   invocation, returns one or three values. The first value tells whether
-   any objects remain in the hash table. When the first value is non-NIL,
-   the second and third values are the key and the value of the next object."
+
+Provides a method of manually looping over the elements of a hash-table.
+FUNCTION is bound to a generator-macro that, within the scope of the
+invocation, returns one or three values. The first value tells whether any
+objects remain in the hash table. When the first value is non-NIL, the second
+and third values are the key and the value of the next object."
+  ;; This essentially duplicates MAPHASH, so any changes here should
+  ;; be reflected there as well.
   (let ((n-function (gensym "WITH-HASH-TABLE-ITERATOR-")))
     `(let ((,n-function
             (let* ((table ,hash-table)
                    (length (length (hash-table-next-vector table)))
                    (index 1))
-              (declare (type (mod #.(floor most-positive-fixnum 2)) index))
+              (declare (type index/2 index))
               (labels
                   ((,function ()
                      ;; (We grab the table again on each iteration just in