(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))
- ;; 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.
- (needing-rehash 0 :type index)
+ ;; 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 free slots in the KV
;; vector.
(next-free-kv 0 :type index)
(index-vector (missing-arg)
:type (simple-array (unsigned-byte #.sb!vm:n-word-bits) (*)))
;; This table parallels the KV vector, and is used to chain together
- ;; the hash buckets, the free list, and the values needing rehash, a
- ;; slot will only ever be in one of these lists.
+ ;; the hash buckets and the free list. A slot will only ever be in
+ ;; one of these lists.
(next-vector (missing-arg)
:type (simple-array (unsigned-byte #.sb!vm:n-word-bits) (*)))
;; This table parallels the KV table, and can be used to store the
;; +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) (*))))
+ ;; Used for locking GETHASH/(SETF GETHASH)/REMHASH
+ (spinlock (sb!thread::make-spinlock :name "hash-table lock")
+ :type sb!thread::spinlock :read-only t)
+ ;; The GC will set this to T if it moves an EQ-based key. This used
+ ;; to be signaled by a bit in the header of the kv vector, but that
+ ;; implementation caused some concurrency issues when we stopped
+ ;; inhibiting GC during hash-table lookup.
+ (needs-rehash-p nil :type (member nil t))
+ ;; Has user requested synchronization?
+ (synchronized-p nil :type (member nil t) :read-only t)
+ ;; For detecting concurrent accesses.
+ #!+sb-hash-table-debug
+ (concurrent-access-error t :type (member nil t))
+ #!+sb-hash-table-debug
+ (accessing-thread nil))
;; as explained by pmai on openprojects #lisp IRC 2002-07-30: #x80000000
;; is bigger than any possible nonEQ hash value, and thus indicates an
;; the generational garbage collector needs to know it.
(defconstant +magic-hash-vector-value+ (ash 1 (1- sb!vm:n-word-bits)))
-\f
(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.
+
+Consequences are undefined if HASH-TABLE is mutated during execution
+of BODY, except for changing or removing elements corresponding to the
+current key. The applies to all threads, not just the curren one --
+even for synchronized hash-tables. If the table may be mutated by
+another thread during iteration, use eg. SB-EXT:WITH-LOCKED-HASH-TABLE
+to protect the WITH-HASH-TABLE-ITERATOR for."
+ ;; 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
(let ((key (aref kv-vector (* 2 index)))
(value (aref kv-vector (1+ (* 2 index)))))
(incf index)
- (unless (and (eq key +empty-ht-slot+)
+ (unless (or (eq key +empty-ht-slot+)
(eq value +empty-ht-slot+))
(return (values t key value))))))))
#',function))))
(macrolet ((,function () '(funcall ,n-function)))
,@body))))
+
+(defmacro-mundanely with-locked-hash-table ((hash-table) &body body)
+ #!+sb-doc
+ "Limits concurrent accesses to HASH-TABLE for the duration of BODY.
+If HASH-TABLE is synchronized, BODY will execute with exclusive
+ownership of the table. If HASH-TABLE is not synchronized, BODY will
+execute with other WITH-LOCKED-HASH-TABLE bodies excluded -- exclusion
+of hash-table accesses not surrounded by WITH-LOCKED-HASH-TABLE is
+unspecified."
+ ;; Needless to say, this also excludes some internal bits, but
+ ;; getting there is too much detail when "unspecified" says what
+ ;; is important -- unpredictable, but harmless.
+ `(sb!thread::with-recursive-spinlock ((hash-table-spinlock ,hash-table))
+ ,@body))
projects / sbcl.git / blobdiff