Extend read library

storage/innobase/CMakeLists.txt

@@ -146,7 +146,6 @@ SET(INNOBASE_SOURCES
     pars/pars0pars.cc
     pars/pars0sym.cc
     que/que0que.cc
-    read/read0read.cc
     row/row0ext.cc
     row/row0ftsort.cc
     row/row0import.cc

storage/innobase/include/trx0trx.h

@@ -445,13 +445,7 @@ from innodb_lock_wait_timeout via trx_t::mysql_thd.
 @return lock wait timeout in seconds */
 #define trx_lock_wait_timeout_get(t) thd_lock_wait_timeout((t)->mysql_thd)
 
-/**
-Determine if the transaction is a non-locking autocommit select
-(implied read-only).
-@param t transaction
-@return true if non-locking autocommit select transaction. */
-#define trx_is_autocommit_non_locking(t) \
-  ((t)->auto_commit && (t)->will_lock == 0)
+#include <innodb/trx_trx/trx_is_autocommit_non_locking.h>
 
 /**
 Determine if the transaction is a non-locking autocommit select

storage/innobase/libs/read/include/innodb/read/ReadView.h

@@ -215,7 +215,7 @@ class ReadView {
   Opens a read view where exactly the transactions serialized before this
   point in time are seen in the view.
   @param id		Creator transaction id */
-  inline void prepare(trx_id_t id);
+  void prepare(trx_id_t id);
 
   /**
   Copy state from another view. Must call copy_complete() to finish.

storage/innobase/libs/read/src/MVCC.cpp

@@ -1,9 +1,16 @@
 #include <innodb/read/MVCC.h>
 
 #include <innodb/allocator/UT_DELETE.h>
-#include <innodb/read/ReadView.h>
 #include <innodb/allocator/UT_NEW_NOKEY.h>
 #include <innodb/logger/error.h>
+#include <innodb/read/ReadView.h>
+#include <innodb/sync_mutex/mutex_enter.h>
+#include <innodb/trx_sys/trx_sys.h>
+#include <innodb/trx_sys/trx_sys_get_max_trx_id.h>
+#include <innodb/trx_sys/trx_sys_mutex_exit.h>
+#include <innodb/trx_trx/trx_is_autocommit_non_locking.h>
+#include <innodb/trx_trx/trx_t.h>
+#include <innodb/trx_sys/trx_sys_mutex_enter.h>
 
 /** Constructor
 @param size		Number of views to pre-allocate */
@@ -169,3 +176,119 @@ void MVCC::view_close(ReadView *&view, bool own_mutex) {
   }
 }
 
+/**
+Allocate and create a view.
+@param view		view owned by this class created for the
+                        caller. Must be freed by calling view_close()
+@param trx		transaction instance of caller */
+void MVCC::view_open(ReadView *&view, trx_t *trx) {
+  ut_ad(!srv_read_only_mode);
+
+  /** If no new RW transaction has been started since the last view
+  was created then reuse the the existing view. */
+  if (view != NULL) {
+    uintptr_t p = reinterpret_cast<uintptr_t>(view);
+
+    view = reinterpret_cast<ReadView *>(p & ~1);
+
+    ut_ad(view->m_closed);
+
+    /* NOTE: This can be optimised further, for now we only
+    resuse the view iff there are no active RW transactions.
+
+    There is an inherent race here between purge and this
+    thread. Purge will skip views that are marked as closed.
+    Therefore we must set the low limit id after we reset the
+    closed status after the check. */
+
+    if (trx_is_autocommit_non_locking(trx) && view->empty()) {
+      view->m_closed = false;
+
+      if (view->m_low_limit_id == trx_sys_get_max_trx_id()) {
+        return;
+      } else {
+        view->m_closed = true;
+      }
+    }
+
+    mutex_enter(&trx_sys->mutex);
+
+    UT_LIST_REMOVE(m_views, view);
+
+  } else {
+    mutex_enter(&trx_sys->mutex);
+
+    view = get_view();
+  }
+
+  if (view != NULL) {
+    view->prepare(trx->id);
+
+    UT_LIST_ADD_FIRST(m_views, view);
+
+    ut_ad(!view->is_closed());
+
+    ut_ad(validate());
+  }
+
+  trx_sys_mutex_exit();
+}
+
+/** Clones the oldest view and stores it in view. No need to
+call view_close(). The caller owns the view that is passed in.
+This function is called by Purge to determine whether it should
+purge the delete marked record or not.
+@param view		Preallocated view, owned by the caller */
+
+void MVCC::clone_oldest_view(ReadView *view) {
+  mutex_enter(&trx_sys->mutex);
+
+  ReadView *oldest_view = get_oldest_view();
+
+  if (oldest_view == NULL) {
+    view->prepare(0);
+
+    trx_sys_mutex_exit();
+
+  } else {
+    view->copy_prepare(*oldest_view);
+
+    trx_sys_mutex_exit();
+
+    view->copy_complete();
+  }
+}
+
+/**
+@return the number of active views */
+
+ulint MVCC::size() const {
+  trx_sys_mutex_enter();
+
+  ulint size = 0;
+
+  for (const ReadView *view = UT_LIST_GET_FIRST(m_views); view != NULL;
+       view = UT_LIST_GET_NEXT(m_view_list, view)) {
+    if (!view->is_closed()) {
+      ++size;
+    }
+  }
+
+  trx_sys_mutex_exit();
+
+  return (size);
+}
+
+
+/**
+Set the view creator transaction id. Note: This shouldbe set only
+for views created by RW transactions.
+@param view		Set the creator trx id for this view
+@param id		Transaction id to set */
+
+void MVCC::set_view_creator_trx_id(ReadView *view, trx_id_t id) {
+  ut_ad(id > 0);
+  ut_ad(mutex_own(&trx_sys->mutex));
+
+  view->creator_trx_id(id);
+}

storage/innobase/libs/read/src/ReadView.cpp

@@ -1,6 +1,8 @@
 #include <innodb/read/ReadView.h>
 
 #include <innodb/allocator/UT_NEW_ARRAY_NOKEY.h>
+#include <innodb/trx_trx/trx_t.h>
+#include <innodb/trx_sys/trx_sys.h>
 
 /** Minimum number of elements to reserve in ReadView::ids_t */
 static const ulint MIN_TRX_IDS = 32;
@@ -234,3 +236,35 @@ void ReadView::copy_complete() {
   m_creator_trx_id = 0;
 }
 
+/**
+Opens a read view where exactly the transactions serialized before this
+point in time are seen in the view.
+@param id		Creator transaction id */
+
+void ReadView::prepare(trx_id_t id) {
+  ut_ad(mutex_own(&trx_sys->mutex));
+
+  m_creator_trx_id = id;
+
+  m_low_limit_no = m_low_limit_id = m_up_limit_id = trx_sys->max_trx_id;
+
+  if (!trx_sys->rw_trx_ids.empty()) {
+    copy_trx_ids(trx_sys->rw_trx_ids);
+  } else {
+    m_ids.clear();
+  }
+
+  ut_ad(m_up_limit_id <= m_low_limit_id);
+
+  if (UT_LIST_GET_LEN(trx_sys->serialisation_list) > 0) {
+    const trx_t *trx;
+
+    trx = UT_LIST_GET_FIRST(trx_sys->serialisation_list);
+
+    if (trx->no < m_low_limit_no) {
+      m_low_limit_no = trx->no;
+    }
+  }
+
+  m_closed = false;
+}

storage/innobase/libs/trx_trx/include/innodb/trx_trx/trx_is_autocommit_non_locking.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <innodb/univ/univ.h>
+
+#include <innodb/trx_trx/trx_t.h>
+
+/**
+Determine if the transaction is a non-locking autocommit select
+(implied read-only).
+@param t transaction
+@return true if non-locking autocommit select transaction. */
+#define trx_is_autocommit_non_locking(t) \
+  ((t)->auto_commit && (t)->will_lock == 0)

storage/innobase/libs/trx_trx/src/CMakeLists.txt

@@ -9,6 +9,7 @@ add_library( ${LIB_NAME} STATIC
     TrxVersion.cpp
     hit_list_t.cpp
     trx_mod_tables_t.cpp
+    trx_is_autocommit_non_locking.cpp
 )
 
 target_compile_options( ${LIB_NAME} PRIVATE  )

storage/innobase/libs/trx_trx/src/trx_is_autocommit_non_locking.cpp

@@ -0,0 +1 @@
+#include <innodb/trx_trx/trx_is_autocommit_non_locking.h>