add a request status, so that multiple clients cannot overwrite requests from other clients

3 files changed, 9 insertions, 20 deletions

diff --git a/src/client/client.cpp b/src/client/client.cpp
index e7853a8..1c0727f 100644
--- a/src/client/client.cpp
+++ b/src/client/client.cpp
@@ -91,20 +91,7 @@ bool Client::request_processed(SharedMemory* shared_memory, int index)
         return false;
     }
 
-    if (shared_memory->full) {
-        return false;
-    }
-    if (shared_memory->tail == shared_memory->head && !shared_memory->full) {
-        return true;
-    }
-
-    for (int i = shared_memory->head; i != shared_memory->tail; i = (i + 1) % QUEUE_SIZE) {
-        if (i == index) {
-            return false;
-        }
-    }
-
-    return true;
+    return shared_memory->request[index].status == PROCESSED;
 }
 
 int Client::send_request(
@@ -117,17 +104,17 @@ int Client::send_request(
 
     pthread_mutex_lock(&shared_memory->mutex);
 
-    while (shared_memory->full) {
+    while (shared_memory->request[shared_memory->tail].status != FREE) {
         pthread_cond_wait(&shared_memory->cond_var, &shared_memory->mutex);
     }
 
     index = shared_memory->tail;
     Request* request = &shared_memory->request[index];
     request->type = type;
+    request->status = SENT;
     strncpy(request->key, k.value_or("null").c_str(), MAX_KEY_SIZE);
     strncpy(request->value, v.value_or("null").c_str(), MAX_VALUE_SIZE);
     shared_memory->tail = (1 + shared_memory->tail) % QUEUE_SIZE;
-    shared_memory->full = shared_memory->head == shared_memory->tail;
     pthread_cond_signal(&shared_memory->cond_var);
 
     pthread_mutex_unlock(&shared_memory->mutex);
@@ -147,6 +134,7 @@ std::string Client::process_respond(SharedMemory* shared_memory, int index)
         pthread_cond_wait(&shared_memory->cond_var, &shared_memory->mutex);
     }
     std::string result(shared_memory->request[index].response);
+    shared_memory->request[index].status = FREE;
     pthread_mutex_unlock(&shared_memory->mutex);
     return result;
 }
diff --git a/src/common/shared_memory.h b/src/common/shared_memory.h
index fe101ea..1798ad1 100644
--- a/src/common/shared_memory.h
+++ b/src/common/shared_memory.h
@@ -14,11 +14,14 @@
  */
 enum Operations { INSERT, DELETE, GET, PRINT };
 
+enum Status { FREE, SENT, PROCESSED};
+
 /**
  * @brief One request constists out of the operation, the arguments and the response.
  */
 struct Request {
     Operations type;
+    Status status = FREE;
     char key[MAX_KEY_SIZE];
     char value[MAX_VALUE_SIZE];
     char response[MAX_VALUE_SIZE];
@@ -38,7 +41,6 @@ struct SharedMemory {
 
     int tail;
     int head;
-    bool full;
 };
 
 /**
diff --git a/src/server/shared_memory_server.h b/src/server/shared_memory_server.h
index d4be69f..e8e5c38 100644
--- a/src/server/shared_memory_server.h
+++ b/src/server/shared_memory_server.h
@@ -34,7 +34,6 @@ public:
             mmap(0, sizeof(SharedMemory), PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
 
         shared_memory->tail = shared_memory->head = 0;
-        shared_memory->full = false;
 
         pthread_mutexattr_t mutex_attr;
         pthread_condattr_t cond_attr;
@@ -74,7 +73,7 @@ public:
         while (true) {
             pthread_mutex_lock(&shared_memory->mutex);
 
-            if (shared_memory->tail == shared_memory->head && !shared_memory->full) {
+            if (shared_memory->request[shared_memory->head].status != SENT) {
                 pthread_cond_wait(&shared_memory->cond_var, &shared_memory->mutex);
             }
 
@@ -140,8 +139,8 @@ public:
             default:
                 break;
             }
+            shared_memory->request[shared_memory->head].status = PROCESSED;
             shared_memory->head = (1 + shared_memory->head) % QUEUE_SIZE;
-            shared_memory->full = false;
             pthread_cond_signal(&shared_memory->cond_var);
             pthread_mutex_unlock(&shared_memory->mutex);
         }