X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fhash-table.lisp;h=ca667447098272a5fb556d7a1669a574ff92f5f8;hb=ae09f8fd7765f6cab6ad317a13e27ff22ab0c11e;hp=8ad97f3b29528e88acc1f2b1bdf61e6b005b2d21;hpb=279283bc1724b60ef9ebbf31ab4837061989be18;p=sbcl.git diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp index 8ad97f3..ca66744 100644 --- a/src/code/hash-table.lisp +++ b/src/code/hash-table.lisp @@ -46,10 +46,6 @@ ;; 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. - (needing-rehash 0 :type index) ;; Index into the Next vector chaining together free slots in the KV ;; vector. (next-free-kv 0 :type index) @@ -61,8 +57,8 @@ (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 @@ -73,8 +69,23 @@ ;; respective key. (hash-vector nil :type (or null (simple-array (unsigned-byte #.sb!vm:n-word-bits) (*)))) - ;; This lock is acquired by %PUTHASH, REMHASH, CLRHASH and GETHASH. - (spinlock (sb!thread::make-spinlock))) + ;; 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 + (signal-concurrent-access t :type (member nil t)) + #!+sb-hash-table-debug + (reading-thread nil) + #!+sb-hash-table-debug + (writing-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 @@ -84,26 +95,32 @@ ;; 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) +(defmacro-mundanely with-hash-table-iterator ((name hash-table) &body body) #!+sb-doc - "WITH-HASH-TABLE-ITERATOR ((function hash-table) &body body) + "WITH-HASH-TABLE-ITERATOR ((name 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. NAME +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 ((function (make-symbol (concatenate 'string (symbol-name name) "-FUN")))) + `(let ((,function (let* ((table ,hash-table) (length (length (hash-table-next-vector table))) (index 1)) (declare (type index/2 index)) (labels - ((,function () + ((,name () ;; (We grab the table again on each iteration just in ;; case it was rehashed by a PUTHASH.) (let ((kv-vector (hash-table-table table))) @@ -112,9 +129,23 @@ and third values are the key and the value of the next object." (let ((key (aref kv-vector (* 2 index))) (value (aref kv-vector (1+ (* 2 index))))) (incf index) - (unless (and (eq key +empty-ht-slot+) - (eq value +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)))) + #',name)))) + (macrolet ((,name () '(funcall ,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))