From 311eae8cfe73340629ddfb3c6a5e6062c7a9b9b4 Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Thu, 20 Oct 2016 13:50:01 +0300
Subject: [PATCH] MXS-983: Add transaction state to session object

---
 include/maxscale/session.h | 83 ++++++++++++++++++++++++++++++++++++++
 server/core/session.c      | 34 ++++++++++++++++
 2 files changed, 117 insertions(+)

diff --git a/include/maxscale/session.h b/include/maxscale/session.h
index c688e6149..0b1cd1d97 100644
--- a/include/maxscale/session.h
+++ b/include/maxscale/session.h
@@ -73,6 +73,36 @@ typedef enum
     SESSION_STATE_DUMMY             /*< dummy session for consistency */
 } session_state_t;
 
+typedef enum
+{
+    SESSION_TRX_INACTIVE_BIT   = 1, /* 0b0001 */
+    SESSION_TRX_ACTIVE_BIT     = 2, /* 0b0010 */
+    SESSION_TRX_READ_ONLY_BIT  = 4, /* 0b0100 */
+    SESSION_TRX_READ_WRITE_BIT = 8, /* 0b1000 */
+} session_trx_state_bit_t;
+
+typedef enum
+{
+    /*< The current transaction state is not known. */
+    SESSION_TRX_UNKNOWN     = 0,
+    /*< There is no on-going transaction. */
+    SESSION_TRX_INACTIVE    = SESSION_TRX_INACTIVE_BIT,
+    /*< A transaction is active. */
+    SESSION_TRX_ACTIVE      = SESSION_TRX_ACTIVE_BIT,
+    /*< An explicit READ ONLY transaction is active. */
+    SESSION_TRX_READ_ONLY   = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_ONLY_BIT),
+    /*< An explicit READ WRITE transaction is active. */
+    SESSION_TRX_READ_WRITE  = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_WRITE_BIT)
+} session_trx_state_t;
+
+/**
+ * Convert transaction state to string representation.
+ *
+ * @param state A transaction state.
+ * @return String representation of the state.
+ */
+const char* session_trx_state_to_string(session_trx_state_t state);
+
 /**
  * The downstream element in the filter chain. This may refer to
  * another filter or to a router.
@@ -150,6 +180,7 @@ typedef struct session
     UPSTREAM        tail;             /*< The tail of the filter chain */
     int             refcount;         /*< Reference count on the session */
     bool            ses_is_child;     /*< this is a child session */
+    session_trx_state_t trx_state;    /*< The current transaction state. */
     skygw_chk_t     ses_chk_tail;
 } SESSION;
 
@@ -206,6 +237,58 @@ RESULTSET *sessionGetList(SESSIONLISTFILTER);
 void process_idle_sessions();
 void enable_session_timeouts();
 
+/**
+ * Get the transaction state of the session.
+ *
+ * @param ses The SESSION object.
+ * @return The transaction state.
+ */
+session_trx_state_t session_get_trx_state(const SESSION* ses);
+
+/**
+ * Set the transaction state of the session.
+ *
+ * NOTE: Only the protocol object may call this.
+ *
+ * @param ses       The SESSION object.
+ * @param new_state The new transaction state.
+ *
+ * @return The previous transaction state.
+ */
+session_trx_state_t session_set_trx_state(SESSION* ses, session_trx_state_t new_state);
+
+/**
+ * Tells whether a transaction is active.
+ *
+ * @return True if a transaction is active, false otherwise.
+ */
+static inline bool session_trx_is_active(const SESSION* ses)
+{
+    return ses->trx_state & SESSION_TRX_ACTIVE_BIT;
+}
+
+/**
+ * Tells whether an explicit READ ONLY transaction is active.
+ *
+ * @return True if an explicit READ ONLY transaction is active,
+ *         false otherwise.
+ */
+static inline bool session_trx_is_read_only(const SESSION* ses)
+{
+    return ses->trx_state == SESSION_TRX_READ_ONLY;
+}
+
+/**
+ * Tells whether an explicit READ WRITE transaction is active.
+ *
+ * @return True if an explicit READ WRITE  transaction is active,
+ *         false otherwise.
+ */
+static inline bool session_trx_is_read_write(const SESSION* ses)
+{
+    return ses->trx_state == SESSION_TRX_READ_WRITE;
+}
+
 MXS_END_DECLS
 
 #endif
diff --git a/server/core/session.c b/server/core/session.c
index a449c6998..f14def029 100644
--- a/server/core/session.c
+++ b/server/core/session.c
@@ -142,6 +142,7 @@ session_alloc(SERVICE *service, DCB *client_dcb)
      */
     session->state = SESSION_STATE_READY;
 
+    session->trx_state = SESSION_TRX_UNKNOWN;
     /*
      * Only create a router session if we are not the listening
      * DCB or an internal DCB. Creating a router session may create a connection to a
@@ -1061,3 +1062,36 @@ sessionGetList(SESSIONLISTFILTER filter)
 }
 /*lint +e429 */
 
+session_trx_state_t session_get_trx_state(const SESSION* ses)
+{
+    return ses->trx_state;
+}
+
+session_trx_state_t session_set_trx_state(SESSION* ses, session_trx_state_t new_state)
+{
+    session_trx_state_t prev_state = ses->trx_state;
+
+    ses->trx_state = new_state;
+
+    return prev_state;
+}
+
+const char* session_trx_state_to_string(session_trx_state_t state)
+{
+    switch (state)
+    {
+    case SESSION_TRX_UNKNOWN:
+        return "SESSION_TRX_UNKNOWN";
+    case SESSION_TRX_INACTIVE:
+        return "SESSION_TRX_INACTIVE";
+    case SESSION_TRX_ACTIVE:
+        return "SESSION_TRX_ACTIVE";
+    case SESSION_TRX_READ_ONLY:
+        return "SESSION_TRX_READ_ONLY";
+    case SESSION_TRX_READ_WRITE:
+        return "SESSION_TRX_READ_WRITE";
+    }
+
+    MXS_ERROR("Unknown session_trx_state_t value: %d", (int)state);
+    return "UNKNOWN";
+}