Encapsulate the main database memory mapping operations (#538)

* Refactor main database server memory mapping operations and other cleanup

* Improve implementation of is_initialized()

* Remove redundant scope_guard

* Remove inadvertently added json file

* Some additional name cleanup and extension of the mapped_data_t functionality

* Extend use of mapped_data_t to database client code

* Rename variables, methods, and type related to mapped data

* Remove state enum and rename is_closed back to is_initialized

* Add a new helper, move helper implementations, and additional renaming

* Update mapped log helper

* Use mapped_log_t helper in client and server

* Update servver log operation

* Update log operations in client code

* Add comments to the new classes

Co-authored-by: Laurentiu Cristofor <[email protected]>

Author: LaurentiuCristofor

production/db/core/inc/db_client.hpp

@@ -7,6 +7,7 @@
 
 #include "gaia/db/db.hpp"
 
+#include "gaia_internal/common/mmap_helpers.hpp"
 #include "gaia_internal/common/retail_assert.hpp"
 #include "gaia_internal/common/system_table_types.hpp"
 #include "gaia_internal/db/triggers.hpp"
@@ -29,14 +30,14 @@ class client
     /**
      * @throws no_open_transaction if there is no active transaction.
      */
-    friend gaia::db::locators_t* gaia::db::get_shared_locators();
+    friend gaia::db::locators_t* gaia::db::get_locators();
 
     /**
      * @throws no_active_session if there is no active session.
      */
-    friend gaia::db::shared_counters_t* gaia::db::get_shared_counters();
-    friend gaia::db::shared_data_t* gaia::db::get_shared_data();
-    friend gaia::db::shared_id_index_t* gaia::db::get_shared_id_index();
+    friend gaia::db::counters_t* gaia::db::get_counters();
+    friend gaia::db::data_t* gaia::db::get_data();
+    friend gaia::db::id_index_t* gaia::db::get_id_index();
 
     friend gaia::db::memory_manager::address_offset_t gaia::db::allocate_object(
         gaia_locator_t locator,
@@ -45,7 +46,7 @@ class client
 public:
     static inline bool is_transaction_active()
     {
-        return (s_locators != nullptr);
+        return (s_private_locators.is_initialized());
     }
 
     /**
@@ -77,16 +78,17 @@ class client
 private:
     // These fields have transaction lifetime.
     thread_local static inline gaia_txn_id_t s_txn_id = c_invalid_gaia_txn_id;
-    thread_local static inline txn_log_t* s_log = nullptr;
-    thread_local static inline int s_fd_log = -1;
+    thread_local static inline mapped_log_t s_log{};
 
-    thread_local static inline locators_t* s_locators = nullptr;
+    thread_local static inline mapped_data_t<locators_t> s_private_locators;
 
     // These fields have session lifetime.
     thread_local static inline int s_fd_locators = -1;
-    thread_local static inline shared_counters_t* s_counters = nullptr;
-    thread_local static inline shared_data_t* s_data = nullptr;
-    thread_local static inline shared_id_index_t* s_id_index = nullptr;
+
+    thread_local static inline mapped_data_t<counters_t> s_shared_counters;
+    thread_local static inline mapped_data_t<data_t> s_shared_data;
+    thread_local static inline mapped_data_t<id_index_t> s_shared_id_index;
+
     thread_local static inline int s_session_socket = -1;
 
     // s_events has transaction lifetime and is cleared after each transaction.
@@ -185,13 +187,13 @@ class client
         }
 
         // We never allocate more than `c_max_log_records` records in the log.
-        if (s_log->count == c_max_log_records)
+        if (s_log.log()->count == c_max_log_records)
         {
             throw transaction_object_limit_exceeded();
         }
 
         // Initialize the new record and increment the record count.
-        txn_log_t::log_record_t* lr = s_log->log_records + s_log->count++;
+        txn_log_t::log_record_t* lr = s_log.log()->log_records + s_log.log()->count++;
         lr->locator = locator;
         lr->old_offset = old_offset;
         lr->new_offset = new_offset;

production/db/core/inc/db_hash_map.hpp

@@ -21,8 +21,8 @@ class db_hash_map
 public:
     static hash_node_t* insert(gaia::common::gaia_id_t id)
     {
-        locators_t* locators = gaia::db::get_shared_locators();
-        shared_id_index_t* id_index = gaia::db::get_shared_id_index();
+        locators_t* locators = gaia::db::get_locators();
+        id_index_t* id_index = gaia::db::get_id_index();
         if (locators == nullptr)
         {
             throw no_open_transaction();
@@ -76,8 +76,8 @@ class db_hash_map
 
     static gaia_locator_t find(gaia::common::gaia_id_t id)
     {
-        locators_t* locators = gaia::db::get_shared_locators();
-        shared_id_index_t* id_index = gaia::db::get_shared_id_index();
+        locators_t* locators = gaia::db::get_locators();
+        id_index_t* id_index = gaia::db::get_id_index();
         if (locators == nullptr)
         {
             throw no_open_transaction();
@@ -109,7 +109,7 @@ class db_hash_map
 
     static void remove(gaia::common::gaia_id_t id)
     {
-        shared_id_index_t* id_index = gaia::db::get_shared_id_index();
+        id_index_t* id_index = gaia::db::get_id_index();
         hash_node_t* node = id_index->hash_nodes + (id % c_hash_buckets);
 
         while (node->id)

production/db/core/inc/db_helpers.hpp

@@ -26,28 +26,28 @@ namespace db
 
 inline gaia_id_t allocate_id()
 {
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    counters_t* counters = gaia::db::get_counters();
     gaia_id_t id = __sync_add_and_fetch(&counters->last_id, 1);
     return id;
 }
 
 inline gaia_type_t allocate_type()
 {
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    counters_t* counters = gaia::db::get_counters();
     gaia_type_t type = __sync_add_and_fetch(&counters->last_type_id, 1);
     return type;
 }
 
 inline gaia_txn_id_t allocate_txn_id()
 {
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    counters_t* counters = gaia::db::get_counters();
     gaia_txn_id_t txn_id = __sync_add_and_fetch(&counters->last_txn_id, 1);
     return txn_id;
 }
 
 inline gaia_locator_t allocate_locator()
 {
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    counters_t* counters = gaia::db::get_counters();
 
     // We need an acquire barrier before reading `last_locator`. We can
     // change this full barrier to an acquire barrier when we change to proper
@@ -81,7 +81,7 @@ inline void update_locator(
     gaia_locator_t locator,
     gaia::db::memory_manager::address_offset_t offset)
 {
-    locators_t* locators = gaia::db::get_shared_locators();
+    locators_t* locators = gaia::db::get_locators();
     if (!locators)
     {
         throw no_open_transaction();
@@ -92,8 +92,8 @@ inline void update_locator(
 
 inline bool locator_exists(gaia_locator_t locator)
 {
-    locators_t* locators = gaia::db::get_shared_locators();
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    locators_t* locators = gaia::db::get_locators();
+    counters_t* counters = gaia::db::get_counters();
 
     // We need an acquire barrier before reading `last_locator`. We can
     // change this full barrier to an acquire barrier when we change to proper
@@ -107,15 +107,15 @@ inline bool locator_exists(gaia_locator_t locator)
 
 inline gaia_offset_t locator_to_offset(gaia_locator_t locator)
 {
-    locators_t* locators = gaia::db::get_shared_locators();
+    locators_t* locators = gaia::db::get_locators();
     return locator_exists(locator)
         ? (*locators)[locator]
         : c_invalid_gaia_offset;
 }
 
 inline db_object_t* offset_to_ptr(gaia_offset_t offset)
 {
-    shared_data_t* data = gaia::db::get_shared_data();
+    data_t* data = gaia::db::get_data();
     return (offset != c_invalid_gaia_offset)
         ? reinterpret_cast<db_object_t*>(data->objects + offset)
         : nullptr;
@@ -130,7 +130,7 @@ inline db_object_t* locator_to_ptr(gaia_locator_t locator)
 // are no memory barriers.
 inline gaia_txn_id_t get_last_txn_id()
 {
-    shared_counters_t* counters = gaia::db::get_shared_counters();
+    counters_t* counters = gaia::db::get_counters();
     return counters->last_txn_id;
 }