MySQL database connection handling

2020-09-08 13:38:28 +01:00
parent 0e37adc86a
commit 8729642387
2 changed files with 377 additions and 0 deletions
--- a/src/database.c
+++ b/src/database.c
@@ -0,0 +1,328 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <mysql.h>
+
+#include "database.h"
+
+
+struct stored_conn_t *storedConnections = 0;
+int nextConnId = 1;
+int defaultTimeout = -1;
+
+
+struct stored_conn_t *connectionById(int conn_id)
+{
+  struct stored_conn_t *ptr = storedConnections;
+
+  while (ptr != 0) {
+    if (ptr->conn_id == conn_id) {
+      return ptr;
+    }
+    ptr = ptr->next;
+  }
+
+  return 0;
+}
+struct stored_conn_t *connectionByName(const char *name)
+{
+  struct stored_conn_t *ptr = storedConnections;
+
+  while (ptr != 0) {
+    if (ptr->name != 0 && strcmp(ptr->name, name) == 0) {
+      return ptr;
+    }
+    ptr = ptr->next;
+  }
+
+  return 0;
+}
+
+
+struct stored_conn_t *createStoredConnection(const char *name)
+{
+  struct stored_conn_t *sconn, *tail;
+
+  if (name && strlen(name) > 0) {
+    if (connectionByName(name) != 0) {
+      fprintf(stderr, "createStoredConnection: Named connection already exists\n");
+      return 0;
+    }
+  }
+
+  sconn = (struct stored_conn_t *)malloc(sizeof(struct stored_conn_t));
+  if (sconn == 0) {
+    fprintf(stderr, "malloc: (%d) %s\n", errno, strerror(errno));
+    return 0;
+  }
+
+  sconn->conn_id = nextConnId++;
+  sconn->name = 0;
+  sconn->conn = (MYSQL *)malloc(sizeof(MYSQL));
+  sconn->isOpen = 0;
+  sconn->isTransact = 0;
+  sconn->needsReset = 0;
+  sconn->timeout = -1;
+  sconn->prev = 0;
+  sconn->next = 0;
+
+  if (sconn->conn == 0) {
+    fprintf(stderr, "malloc: (%d) %s\n", errno, strerror(errno));
+    destroyStoredConnection(sconn);
+    return 0;
+  }
+
+  if (name && strlen(name) > 0) {
+    sconn->name = (char *)malloc(sizeof(char) * strlen(name));
+    if (sconn->name == 0) {
+      fprintf(stderr, "malloc: (%d) %s\n", errno, strerror(errno));
+      destroyStoredConnection(sconn);
+      return 0;
+    }
+    memcpy(sconn->name, name, strlen(name) * sizeof(char));
+  }
+
+  if (mysql_init(sconn->conn) == 0) {
+    fprintf(stderr, "mysql_init: unknown error\n");
+    destroyStoredConnection(sconn);
+    return 0;
+  }
+
+  if (defaultTimeout >= 0) {
+    setTimeout(sconn, defaultTimeout);
+  }
+
+  if (storedConnections == 0) {
+    storedConnections = sconn;
+  } else {
+    tail = storedConnections;
+    while (tail->next != 0) {
+      tail = tail->next;
+    }
+    tail->next = sconn;
+    sconn->prev = tail;
+  }
+
+  return sconn;
+}
+struct stored_conn_t *resetStoredConnection(struct stored_conn_t *sconn)
+{
+  MYSQL *new_conn;
+
+  new_conn = (MYSQL *)malloc(sizeof(MYSQL));
+  if (new_conn == 0) {
+    fprintf(stderr, "malloc: (%d) %s\n", errno, strerror(errno));
+    return 0;
+  }
+
+  if (mysql_init(new_conn) == 0) {
+    fprintf(stderr, "mysql_init: unknown error\n");
+    return 0;
+  }
+
+  free(sconn->conn);
+  sconn->conn = new_conn;
+
+  if (sconn->timeout >= 0) {
+    setTimeout(sconn, sconn->timeout);
+  }
+
+  sconn->needsReset = 0;
+
+  return sconn;
+}
+void destroyStoredConnection(struct stored_conn_t *sconn)
+{
+  if (sconn->isTransact) {
+    // rollback transaction
+  }
+
+  if (sconn->isOpen) {
+    mysql_close(sconn->conn);
+  }
+
+  if (sconn->name) {
+    free(sconn->name);
+    sconn->name = 0;
+  }
+
+  if (sconn->conn) {
+    free(sconn->conn);
+    sconn->conn = 0;
+  }
+
+  if (sconn->prev) {
+    sconn->prev->next = sconn->next;
+  } else {
+    storedConnections = sconn->next;
+  }
+
+  if (sconn->next) {
+    sconn->next->prev = sconn->prev;
+  }
+
+  free(sconn);
+}
+void destroyAllConnections()
+{
+  struct stored_conn_t *ptr = storedConnections;
+
+  while (ptr != 0 && ptr->next != 0) {
+    ptr = ptr->next;
+    destroyStoredConnection(ptr->prev);
+  }
+
+  if (ptr != 0) {
+    destroyStoredConnection(ptr);
+  }
+}
+
+
+int connectionCount()
+{
+  int i = 0;
+  struct stored_conn_t *ptr = storedConnections;
+
+  while (ptr != 0) {
+    i++;
+    ptr = ptr->next;
+  }
+
+  return i;
+}
+
+
+int setTimeout(struct stored_conn_t *sconn, unsigned int timeout)
+{
+  sconn->timeout = timeout;
+
+  if (mysql_optionsv(sconn->conn, MYSQL_OPT_CONNECT_TIMEOUT, (void *)&timeout) != 0) {
+    return -1;
+  }
+  if (mysql_optionsv(sconn->conn, MYSQL_OPT_READ_TIMEOUT, (void *)&timeout) != 0) {
+    return -1;
+  }
+  if (mysql_optionsv(sconn->conn, MYSQL_OPT_WRITE_TIMEOUT, (void *)&timeout) != 0) {
+    return -1;
+  }
+
+  return 0;
+}
+void setDefaultTimeout(unsigned int timeout)
+{
+  defaultTimeout = timeout;
+}
+
+
+int connectToHost(struct stored_conn_t *sconn, 
+                  const char *host, unsigned int port,
+                  const char *user, const char *passwd, const char *db)
+{
+  MYSQL *ret;
+  int freeCon = 0;
+
+  if (sconn == NULL) {
+    sconn = createStoredConnection(NULL);
+    if (sconn == 0) {
+      return -1;
+    }
+    freeCon = 1;
+  }
+
+  if (sconn->isOpen) {
+    fprintf(stderr, "connectToHost: Connection already open\n");
+    return -1;
+  }
+
+  if (sconn->needsReset && resetStoredConnection(sconn) != sconn) {
+    return -1;
+  }
+
+  ret = mysql_real_connect(sconn->conn, host, user, passwd, db, port, NULL, 0);
+  // flags: CLIENT_MULTI_STATEMENTS
+
+  if (ret == 0) {
+    fprintf(
+      stderr, "mysql_real_connect: (%d) %s\n", mysql_errno(sconn->conn), mysql_error(sconn->conn)
+    );
+    sconn->needsReset = 1;
+    errno = -mysql_errno(sconn->conn);
+    if (freeCon) {
+      destroyStoredConnection(sconn);
+    }
+    return errno;
+  }
+
+  sconn->isOpen = 1;
+
+  return sconn->conn_id;
+}
+int connectToSocket(struct stored_conn_t *sconn,
+                    const char *unix_socket,
+                    const char *user, const char *passwd, const char *db)
+{
+  MYSQL *ret;
+  int freeCon = 0;
+
+  if (sconn == NULL) {
+    sconn = createStoredConnection(NULL);
+    if (sconn == 0) {
+      return -1;
+    }
+    freeCon = 1;
+  }
+
+  if (sconn->isOpen) {
+    fprintf(stderr, "connectToSocket: Connection already open\n");
+    return -1;
+  }
+
+  if (sconn->needsReset && resetStoredConnection(sconn) != sconn) {
+    return -1;
+  }
+
+  ret = mysql_real_connect(sconn->conn, NULL, user, passwd, db, 0, unix_socket, 0);
+  // flags: CLIENT_MULTI_STATEMENTS
+
+  if (ret == 0) {
+    fprintf(
+      stderr, "mysql_real_connect: (%d) %s\n", mysql_errno(sconn->conn), mysql_error(sconn->conn)
+    );
+    sconn->needsReset = 1;
+    errno = -mysql_errno(sconn->conn);
+    if (freeCon) {
+      destroyStoredConnection(sconn);
+    }
+    return errno;
+  }
+
+  sconn->isOpen = 1;
+
+  return sconn->conn_id;
+}
+
+void closeConnection(struct stored_conn_t *sconn)
+{
+  if (sconn->isTransact) {
+    // rollback transaction
+  }
+
+  if (sconn->isOpen) {
+    mysql_close(sconn->conn);
+  }
+
+  sconn->needsReset = 1;
+  sconn->isOpen = 0;
+}
+
+void closeAllConnections()
+{
+  struct stored_conn_t *c, *ptr = storedConnections;
+
+  while (ptr != 0) {
+    c = ptr;
+    ptr = ptr->next;
+    destroyStoredConnection(c);
+  }
+}
--- a/src/database.h
+++ b/src/database.h
@@ -0,0 +1,49 @@
+#ifndef __DATABASE_H__
+#define __DATABASE_H__
+
+#include <mysql.h>
+
+struct stored_conn_t {
+  int conn_id;
+  char *name;
+
+  MYSQL *conn;
+
+  int isOpen     :1;
+  int isTransact :1;
+  int needsReset :1;
+  int __FLAGS;
+
+  unsigned int timeout;
+
+  struct stored_conn_t *prev;
+  struct stored_conn_t *next;
+};
+
+
+struct stored_conn_t *connectionById(int conn_id);
+struct stored_conn_t *connectionByName(const char *name);
+
+
+struct stored_conn_t *createStoredConnection(const char *name);
+struct stored_conn_t *resetStoredConnection(struct stored_conn_t *sconn);
+void destroyStoredConnection(struct stored_conn_t *sconn);
+void destroyAllConnections();
+
+int connectionCount();
+
+int setTimeout(struct stored_conn_t *sconn, unsigned int timeout);
+void setDefaultTimeout(unsigned int timeout);
+
+
+int connectToHost(struct stored_conn_t *sconn, 
+                  const char *host, unsigned int port,
+                  const char *user, const char *passwd, const char *db);
+int connectToSocket(struct stored_conn_t *sconn,
+                    const char *unix_socket,
+                    const char *user, const char *passwd, const char *db);
+
+void closeConnection(struct stored_conn_t *sconn);
+void closeAllConnections();
+
+#endif // __DATABASE_H__