From e5997403e61f46f23255becf22ce8e05a4982405 Mon Sep 17 00:00:00 2001 From: =?utf8?q?J=C3=A9r=C3=B4me=20Benoit?= Date: Mon, 26 Feb 2018 23:26:53 +0100 Subject: [PATCH] Add posix semaphore course example code. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Signed-off-by: Jérôme Benoit --- .gitignore | 1 + semaphore/Makefile | 83 +++++++++++++++++++++++++++++++++++++++++++ semaphore/semaphore.c | 44 +++++++++++++++++++++++ 3 files changed, 128 insertions(+) create mode 100644 semaphore/Makefile create mode 100644 semaphore/semaphore.c diff --git a/.gitignore b/.gitignore index 728eb36..18e9abd 100644 --- a/.gitignore +++ b/.gitignore @@ -4,6 +4,7 @@ philosophe/philosophe prodcons/prodcons rw/reader/reader rw/writer/writer +semaphore/semaphore signal/signaux0 threads/exemple1 upipe/upipe diff --git a/semaphore/Makefile b/semaphore/Makefile new file mode 100644 index 0000000..12f70af --- /dev/null +++ b/semaphore/Makefile @@ -0,0 +1,83 @@ +# Sample Makefile to build simple project. +# +# This Makefile expect all source files (.c) to be at the same level, in the +# current working directory. +# +# It will automatically generate dependencies, compile all files, and produce a +# binary using the provided name. +# +# Set BINARY_NAME to the name of the binary file to build. +# Set BUILD_TYPE to either debug or release +# +# Automatic dependencies code from: +# http://make.mad-scientist.net/papers/advanced-auto-dependency-generation/#tldr +BINARY_NAME=semaphore +BUILD_TYPE=debug +#BUILD_TYPE=release +LDLIBS=-lpthread + +# ==================================== +# DO NOT CHANGE STUFF BEYOND THIS LINE +# ==================================== + +all: $(BINARY_NAME) + +CC=gcc +LD=gcc + +WARN_FLAGS = -Wall -Wextra +STD_FLAG = -std=c11 + +ifeq ($(BUILD_TYPE),debug) +BUILDDIR := .build/debug +DEBUG_FLAG = -g +DEBUG = 1 +STRIP_FLAG = +OPTI_FLAG = -O0 +else +BUILDDIR := .build/release +DEBUG_FLAG = +DEBUG = 0 +STRIP_FLAG = -s +OPTI_FLAG = -O3 +endif + +CFLAGS := -DDEBUG=$(DEBUG) $(CFLAGS) $(WARN_FLAGS) $(STD_FLAG) $(OPTI_FLAG) $(DEBUG_FLAG) +LDFLAGS := $(LDFLAGS) $(STRIP_FLAG) + +OBJDIR := $(BUILDDIR)/objs +$(shell mkdir -p $(OBJDIR)) + +SRCS=$(wildcard *.c) +OBJS=$(patsubst %.c,$(OBJDIR)/%.o,$(SRCS)) + +DEPDIR := $(BUILDDIR)/deps +$(shell mkdir -p $(DEPDIR)) +DEPFLAGS = -MT $@ -MMD -MP -MF $(DEPDIR)/$*.Td +POSTCOMPILE = mv -f $(DEPDIR)/$*.Td $(DEPDIR)/$*.d + +$(BINARY_NAME): $(OBJS) + @echo "[LD ] $@" + @$(LD) $(CFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@ + +$(OBJDIR)/%.o: %.c $(DEPDIR)/%.d + @echo "[C ] $*" + @$(CC) $(DEPFLAGS) $(CFLAGS) -c $< -o $@ + @$(POSTCOMPILE) + +$(DEPDIR)/%.d: ; + +.PRECIOUS: $(DEPDIR)/%.d + +include $(wildcard $(patsubst %,$(DEPDIR)/%.d,$(basename $(SRCS)))) + +clean: + @echo "[CLN]" + -@rm -r $(BUILDDIR) + -@rm $(BINARY_NAME) + +disassemble: $(BINARY_NAME) + objdump -d $< | less + +symbols: $(BINARY_NAME) + objdump -t $< | sort | less diff --git a/semaphore/semaphore.c b/semaphore/semaphore.c new file mode 100644 index 0000000..28eadba --- /dev/null +++ b/semaphore/semaphore.c @@ -0,0 +1,44 @@ +#include // pour les sémaphores +#include // pour pthread_create et pthread_join +#include // pour printf + +#define val 1 +sem_t mutex; // sémaphore +int var_glob = 0; + +void *increment(void *); +void *decrement(void *); + +int main() +{ + pthread_t threadA, threadB; + sem_init(&mutex, 0, val); // initialiser mutex + printf("ici main : var_glob = %d\n", var_glob); + // création d'un thread pour increment + pthread_create(&threadA, NULL, increment, NULL); + // création d'un thread pour decrement + pthread_create(&threadB, NULL, decrement, NULL); + // attendre la fin des threads + pthread_join(threadA, NULL); + pthread_join(threadB, NULL); + printf("ici main, fin threads : var_glob =%d \n", var_glob); + return 0; +} + +void *decrement(void *nothing) +{ + sem_wait(&mutex); // attendre l'autorisation d'accès + var_glob = var_glob - 1; + printf("ici sc de decrement: var_glob= %d\n", var_glob); + sem_post(&mutex); + return (NULL); +} + +void *increment(void *nothing) +{ + sem_wait(&mutex); + var_glob = var_glob + 1; + printf("ici sc de increment: var_glob= %d\n", var_glob); + sem_post(&mutex); + return (NULL); +} -- 2.34.1