ch3

ch3/ex3-39.scm

@@ -3,4 +3,10 @@
 (define x 10)
 (define s (make-serializer))
 (parallel-execute (lambda () (set! x ((s (lambda () (* x x))))))
-                  (s (lambda () (set! x (+ x 1)))))
+                  (s (lambda () (set! x (+ x 1)))))
+
+x
+
+;; 121
+;; 101
+;; 11

ch3/ex3-40.scm

@@ -0,0 +1,13 @@
+;; Example 3.40
+
+(define x 10)
+(parallel-execute (lambda () (set! x (* x x)))
+                  (lambda () (set! x (* x x x))))
+
+;; 100
+;; 1000
+;; 1000000
+;; 10000
+;; 100000
+
+;; serialized: 1000000

ch3/ex3-41.scm

@@ -0,0 +1,28 @@
+;; Example 3.41
+
+(define (make-account balance)
+  (define (withdraw amount)
+    (if (>= balance amount)
+        (begin (set! balance (- balance amount))
+               balance)
+        "Insufficient funds\n"))
+
+  (define (deposit amount)
+    (set! balance (+ balance amount))
+    balance)
+
+  (let ((protected (make-serializer)))
+    (define (dispatch m)
+      (cond ((eq? m 'withdraw) (protected withdraw))
+            ((eq? m 'deposit) (protected deposit))
+            ((eq? m 'balance) ((protected (lambda () balance))))
+            (else (error "Unknown request" m))))
+    dispatch))
+
+;; A = make-account
+
+;; parallel:
+;; balance = A.get-balance
+;; A.make-withdraw
+
+;; balance maybe wrong

ch3/ex3-42.scm

@@ -0,0 +1,24 @@
+;; Example 3.42
+
+(define (make-account balance)
+  (define (withdraw amount)
+    (if (>= balance amount)
+        (begin (set! balance (- balance amount))
+               balance)
+        "Insufficient funds\n"))
+
+  (define (deposit amount)
+    (set! balance (+ balance amount))
+    balance)
+
+  (let ((protected (make-serializer)))
+    (let ((protected-withdraw (protected withdraw))
+          (protected-deposit (protected deposit)))
+      (define (dispatch m)
+        (cond ((eq? m 'withdraw) protected-withdraw)
+              ((eq? m 'deposit) protected-deposit)
+              ((eq? m 'balance) balance)
+              (else (error "Unknown request" m))))
+      dispatch)))
+
+;; it's okay, no difference

ch3/ex3-43.scm

@@ -0,0 +1,3 @@
+;; Example 3.43
+
+;; on the paper

ch3/ex3-44.scm

@@ -0,0 +1,5 @@
+(define (transfer from-account to-account amount)
+  ((from-account 'withdraw) amount)
+  ((to-account 'deposit) amount))
+
+;; no problem here

ch3/ex3-45.scm

@@ -0,0 +1,3 @@
+;; Example 3.45
+
+;; withdraw and deposit serialized twice by the same serializer

ch3/ex3-47.scm

@@ -0,0 +1,4 @@
+;; Example 3.47
+
+(define (make-semaphore n)
+

ch3/test_concurrency_2.scm

@@ -0,0 +1,35 @@
+;; test concurrency
+
+(require rnrs/mutable-pairs-6)
+
+(define (my-test-and-set! cell)
+  (if (car cell)
+      #t
+      (begin (set-car! cell #t)
+             #f)))
+
+(define (my-make-mutex)
+  (let ((cell (list #f)))
+    (define (the-mutex m)
+      (cond ((eq? m 'acquire)
+             (if (my-test-and-set! cell)
+                 (the-mutex 'acquire)))
+            ((eq? m 'release) (clear! cell))))
+    the-mutex))
+
+(define (my-make-serializer)
+  (let ((mutex (my-make-mutex)))
+    (lambda (p)
+      (define (serialized-p . args)
+        (mutex 'acquire)
+        (let ((val (apply p args)))
+          (mutex 'release)
+          val))
+      serialized-p)))
+
+(define x 10)
+(define s (my-make-serializer))
+(parallel-execute (s (lambda () (set! x (* x x))))
+                  (s (lambda () (set! x (+ x 1)))))
+
+x

ch3/test_streams.scm

@@ -0,0 +1,30 @@
+#lang racket
+
+(define (cons-stream a b)
+  (cons a (stream-delay b)))
+
+(define (stream-car stream)
+  (car stream))
+
+(define (stream-cdr stream)
+  (stream-force (cdr stream)))
+
+(define (stream-ref s n)
+  (if (= n 0)
+      (stream-car s)
+      (stream-ref (stream-cdr s) (- n 1))))
+
+(define (stream-map proc s)
+  (if (stream-null? s)
+      the-empty-stream
+      (cons-stream (proc (stream-car s))
+                   (stream-map proc (stream-cdr s)))))
+
+(define (stream-for-each proc s)
+  (if (stream-null? s)
+      'done
+      (begin (proc (stream-car s))
+             (stream-for-each proc (stream-cdr s)))))
+
+(define (display-stream s)
+  (stream-for-each (lambda (x) (newline) (display x)) s))