1.0.22.18: select() and EAGAIN

[sbcl.git] / src / code / hash-table.lisp

diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp
index aeab5f1..5eb7a3c 100644 (file)
--- a/src/code/hash-table.lisp
+++ b/src/code/hash-table.lisp
@@ -69,18 +69,23 @@
   ;; respective key.
   (hash-vector nil :type (or null (simple-array (unsigned-byte
                                                  #.sb!vm:n-word-bits) (*))))
-  ;; Used for locking GETHASH/(SETF GETHASH)/REMHASH for tables with :LOCK-P T
-  (spinlock (sb!thread::make-spinlock) :type sb!thread::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
-  (concurrent-access-error t :type (member nil t))
+  (signal-concurrent-access t :type (member nil t))
   #!+sb-hash-table-debug
-  (accessing-thread nil))
+  (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
@@ -90,7 +95,6 @@
 ;; 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)
@@ -99,7 +103,14 @@ 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."
+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-")))
@@ -124,3 +135,17 @@ and third values are the key and the value of the next object."
                 #',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))