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116 lines
2.5 KiB
116 lines
2.5 KiB
/*
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* Copyright (c) 2016 - present Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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package codetoanalyze.java.checkers;
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import javax.annotation.concurrent.ThreadSafe;
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class OurThreadUtils{
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void assertMainThread(){}
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void assertHoldsLock(Object lock){}
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}
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@ThreadSafe
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class RaceWithMainThread{
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Integer f;
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OurThreadUtils o;
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void main_thread_OK(){
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o.assertMainThread();
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f = 88;
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}
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void main_thread_indirect_OK() {
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main_thread_OK();
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f = 77;
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}
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void read_from_main_thread_OK(){
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Integer x;
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o.assertMainThread();
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x = f;
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}
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void read_unprotected_unthreaded_Bad(){
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Integer x;
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x = f;
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}
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/*There is a particularly subtle idiom which avoids races, where a
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variable can be read without protection on the main thread, if
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it is written with protection on the main thread and read with
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protection off. The next three methods do this safely, and the fourth
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unsafely.
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*/
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Integer i;
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void protected_write_on_main_thread_OK() {
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o.assertMainThread();
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synchronized (this) {
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i = 99;
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}
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}
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void unprotected_read_on_main_thread_OK() {
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Integer x;
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o.assertMainThread();
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x = i;
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}
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void protected_read_off_main_thread_OK() {
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Integer x;
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synchronized (this) {
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x = i;
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}
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}
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void readProtectedUnthreadedBad(){
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Integer x;
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synchronized (this){
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x = f;
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}
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}
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Integer g;
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void holds_lock_OK(){
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o.assertHoldsLock(this);
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g = 88;
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}
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void holds_lock_indirect_OK() {
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holds_lock_OK();
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g = 77;
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}
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/* This was a source of false positives until we interpreted join of threaded
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by || instead of &&; see BooleanOr in ThreadSafetyDomain.ml */
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void conditional_Ok(boolean b){
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if (b)
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{ /*People not literally putting this assert inside if's,
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but implicitly by method calls */
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o. assertMainThread();
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f = 88;
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} /* BooleanAnd for threaded would hose you here and lead to a report */
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}
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/* On the other hand, BooleanOr leads to false negatives, which we should
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fix with a more refined abstract domain (without going all the way to disjuntions) */
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void FN_conditional_Bad(boolean b){
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if (b)
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{
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o.assertMainThread();
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f = 88;
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} else {
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f = 99; // Using || hoses this; no report
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}
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}
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}
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