From b941fca02a635305ea541f92fd701d550704cbbf Mon Sep 17 00:00:00 2001
From: Fabio Scotto di Santolo <fabio.scottodisantolo@gmail.com>
Date: Wed, 28 Aug 2024 18:18:10 +0200
Subject: [PATCH] Modify PID Manager with threads

---
 threads/ex417.c                   | 31 ++++++++++++++
 threads/pid_manager.c             |  2 +-
 threads/pid_manager.h             |  1 +
 threads/pid_manager_thread_chp4.c | 70 +++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 threads/ex417.c
 create mode 100644 threads/pid_manager_thread_chp4.c

diff --git a/threads/ex417.c b/threads/ex417.c
new file mode 100644
index 0000000..2e23c3b
--- /dev/null
+++ b/threads/ex417.c
@@ -0,0 +1,31 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int value = 0;
+void *runner(void *param);
+
+int main(int argc, char *argv[]) {
+  pid_t pid;
+  pthread_t tid;
+  pthread_attr_t attr;
+
+  pid = fork();
+
+  if (pid == 0) {
+    pthread_attr_init(&attr);
+    pthread_create(&tid, &attr, runner, NULL);
+    pthread_join(tid, NULL);
+    printf("CHILD: value = %d\n", value);
+  } else if (pid > 0) {
+    wait(NULL);
+    printf("PARENT: value = %d\n", value);
+  }
+}
+
+void *runner(void *param) {
+  value = 5;
+  pthread_exit(0);
+}
diff --git a/threads/pid_manager.c b/threads/pid_manager.c
index bd21294..7538b76 100644
--- a/threads/pid_manager.c
+++ b/threads/pid_manager.c
@@ -34,7 +34,7 @@ void release_pid(int pid) {
 
 int main(void) {
   if (allocate_map() != 1) {
-    perror("Failed to initialiaze PID Manager\n");
+    perror("Failed to initialize PID Manager\n");
     exit(1);
   }
 
diff --git a/threads/pid_manager.h b/threads/pid_manager.h
index a8011f8..e116507 100644
--- a/threads/pid_manager.h
+++ b/threads/pid_manager.h
@@ -1,5 +1,6 @@
 #if !defined(__PID_MANGER_H__)
 #define __PID_MANGER_H__
+#define _GNU_SOURCE
 
 // Crea e inizializza una struttura per rappresentare i pid;
 // restituisce -1 in caso di insuccesso e 1 in caso di successo.
diff --git a/threads/pid_manager_thread_chp4.c b/threads/pid_manager_thread_chp4.c
new file mode 100644
index 0000000..761dcfd
--- /dev/null
+++ b/threads/pid_manager_thread_chp4.c
@@ -0,0 +1,70 @@
+#include "pid_manager.h"
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define MIN_PID 300
+#define MAX_PID 5000
+#define SIZE (MAX_PID - MIN_PID + 1)
+
+bool pids[SIZE];
+
+void *runner(void *param);
+
+int allocate_map(void) {
+  for (int i = 0; i < SIZE; i++) {
+    pids[i] = false;
+  }
+  return 1;
+}
+
+int allocate_pid(void) {
+  for (int i = 0; i < SIZE; i++) {
+    if (!pids[i]) {
+      pids[i] = true;
+      return i + MIN_PID;
+    }
+  }
+  return -1;
+}
+
+void release_pid(int pid) {
+  if (pid >= MIN_PID && pid <= MAX_PID) {
+    pids[pid - MIN_PID] = false;
+  }
+}
+
+void *runner(void *param) {
+  const pid_t self = gettid();
+  const int pid = allocate_pid();
+  printf("Run thread %d handle PID %d.\n", self, pid);
+  sleep(rand() % 31);
+  release_pid(pid);
+  printf("Thread %d ended\n", self);
+  pthread_exit(0);
+}
+
+int main(void) {
+  const int thread_count = 100;
+  pthread_t threads[thread_count];
+
+  if (!allocate_map()) {
+    perror("Failed to allocate PID Manager\n");
+    exit(EXIT_FAILURE);
+  }
+
+  for (int i = 0; i < thread_count; i++) {
+    printf("Created thread %d\n", i);
+    pthread_create(&threads[i], NULL, runner, NULL);
+  }
+
+  for (int i = 0; i < thread_count; i++) {
+    printf("Waiting thread %d\n", i);
+    pthread_join(threads[i], NULL);
+  }
+
+  return EXIT_SUCCESS;
+}