--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Common/DatabaseManager.cpp	Wed Jul 04 08:16:29 2018 +0200
@@ -0,0 +1,439 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#include "DatabaseManager.h"
+
+#include <Core/Logging.h>
+#include <Core/OrthancException.h>
+
+#include <boost/thread.hpp>
+
+namespace OrthancDatabases
+{
+  IDatabase& DatabaseManager::GetDatabase()
+  {
+    static const unsigned int MAX_CONNECTION_ATTEMPTS = 10;   // TODO: Parameter
+
+    unsigned int count = 0;
+      
+    while (database_.get() == NULL)
+    {
+      transaction_.reset(NULL);
+
+      try
+      {
+        database_.reset(factory_->Open());
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        if (e.GetErrorCode() == Orthanc::ErrorCode_DatabaseUnavailable)
+        {
+          count ++;
+
+          if (count <= MAX_CONNECTION_ATTEMPTS)
+          {
+            LOG(WARNING) << "Database is currently unavailable, retrying...";
+            boost::this_thread::sleep(boost::posix_time::seconds(1));
+            continue;
+          }
+          else
+          {
+            LOG(ERROR) << "Timeout when connecting to the database, giving up";
+          }
+        }
+
+        throw;
+      }
+    }
+
+    if (database_.get() == NULL ||
+        database_->GetDialect() != dialect_)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+    else
+    {
+      return *database_;
+    }
+  }
+
+
+  void DatabaseManager::Close()
+  {
+    LOG(TRACE) << "Closing the connection to the database";
+
+    // Rollback active transaction, if any
+    transaction_.reset(NULL);
+
+    // Delete all the cached statements (must occur before closing
+    // the database)
+    for (CachedStatements::iterator it = cachedStatements_.begin();
+         it != cachedStatements_.end(); ++it)
+    {
+      assert(it->second != NULL);
+      delete it->second;
+    }
+
+    cachedStatements_.clear();
+
+    // Close the database
+    database_.reset(NULL);
+
+    LOG(TRACE) << "Connection to the database is closed";
+  }
+
+    
+  void DatabaseManager::CloseIfUnavailable(Orthanc::ErrorCode e)
+  {
+    if (e != Orthanc::ErrorCode_Success)
+    {
+      transaction_.reset(NULL);
+    }
+
+    if (e == Orthanc::ErrorCode_DatabaseUnavailable)
+    {
+      LOG(ERROR) << "The database is not available, closing the connection";
+      Close();
+    }
+  }
+
+
+  IPrecompiledStatement* DatabaseManager::LookupCachedStatement(const StatementLocation& location) const
+  {
+    CachedStatements::const_iterator found = cachedStatements_.find(location);
+
+    if (found == cachedStatements_.end())
+    {
+      return NULL;
+    }
+    else
+    {
+      assert(found->second != NULL);
+      return found->second;
+    }
+  }
+
+    
+  IPrecompiledStatement& DatabaseManager::CacheStatement(const StatementLocation& location,
+                                                         const Query& query)
+  {
+    LOG(TRACE) << "Caching statement from " << location.GetFile() << ":" << location.GetLine();
+      
+    std::auto_ptr<IPrecompiledStatement> statement(GetDatabase().Compile(query));
+      
+    IPrecompiledStatement* tmp = statement.get();
+    if (tmp == NULL)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
+    }
+
+    assert(cachedStatements_.find(location) == cachedStatements_.end());
+    cachedStatements_[location] = statement.release();
+
+    return *tmp;
+  }
+
+    
+  ITransaction& DatabaseManager::GetTransaction()
+  {
+    if (transaction_.get() == NULL)
+    {
+      LOG(TRACE) << "Automatically creating a database transaction";
+
+      try
+      {
+        transaction_.reset(GetDatabase().CreateTransaction());
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        CloseIfUnavailable(e.GetErrorCode());
+        throw;
+      }
+    }
+
+    assert(transaction_.get() != NULL);
+    return *transaction_;
+  }
+
+    
+  DatabaseManager::DatabaseManager(IDatabaseFactory* factory) :  // Takes ownership
+    factory_(factory)
+  {
+    if (factory == NULL)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+    }
+
+    dialect_ = factory->GetDialect();
+  }
+
+  
+  void DatabaseManager::StartTransaction()
+  {
+    boost::recursive_mutex::scoped_lock lock(mutex_);
+
+    try
+    {
+      if (transaction_.get() != NULL)
+      {
+#if 0
+        // TODO: This should be the right implementation
+        if (transaction_->IsReadOnly())
+        {
+          LOG(TRACE) << "Rollback of an uncommitted read-only transaction to start another transaction";
+          transaction_->Rollback();
+          transaction_.reset(NULL);
+        }
+        else
+        {
+          LOG(ERROR) << "Cannot rollback an uncommitted write transaction to start another transaction";
+          throw Orthanc::OrthancException(Orthanc::ErrorCode_Database);
+        }
+#else
+        LOG(INFO) << "Committing an uncommitted transaction to start another transaction";
+        transaction_->Commit();
+        transaction_.reset(NULL);
+#endif
+      }
+
+      transaction_.reset(GetDatabase().CreateTransaction());
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+  
+
+  void DatabaseManager::CommitTransaction()
+  {
+    boost::recursive_mutex::scoped_lock lock(mutex_);
+
+    if (transaction_.get() == NULL)
+    {
+      LOG(ERROR) << "Cannot commit a non-existing transaction";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+    else
+    {
+      try
+      {
+        transaction_->Commit();
+        transaction_.reset(NULL);
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        CloseIfUnavailable(e.GetErrorCode());
+        throw;
+      }
+    }
+  }
+
+
+  void DatabaseManager::RollbackTransaction()
+  {
+    boost::recursive_mutex::scoped_lock lock(mutex_);
+
+    if (transaction_.get() == NULL)
+    {
+      LOG(ERROR) << "Cannot rollback a non-existing transaction";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+    else
+    {
+      try
+      {
+        transaction_->Rollback();
+        transaction_.reset(NULL);
+      }
+      catch (Orthanc::OrthancException& e)
+      {
+        CloseIfUnavailable(e.GetErrorCode());
+        throw;
+      }
+    }
+  }
+
+
+  IResult& DatabaseManager::CachedStatement::GetResult() const
+  {
+    if (result_.get() == NULL)
+    {
+      LOG(ERROR) << "Accessing the results of a statement without having executed it";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+
+    return *result_;
+  }
+
+
+  DatabaseManager::CachedStatement::CachedStatement(const StatementLocation& location,
+                                                    DatabaseManager& manager,
+                                                    const char* sql) :
+    lock_(manager.mutex_),
+    manager_(manager),
+    location_(location),
+    database_(manager.GetDatabase()),
+    transaction_(manager.GetTransaction())
+  {
+    statement_ = manager_.LookupCachedStatement(location);
+
+    if (statement_ == NULL)
+    {
+      query_.reset(new Query(sql));
+    }
+    else
+    {
+      LOG(TRACE) << "Reusing cached statement from "
+                 << location.GetFile() << ":" << location.GetLine();
+    }
+  }
+
+      
+  void DatabaseManager::CachedStatement::SetReadOnly(bool readOnly)
+  {
+    if (query_.get() != NULL)
+    {
+      query_->SetReadOnly(readOnly);
+    }
+  }
+
+
+  void DatabaseManager::CachedStatement::SetParameterType(const std::string& parameter,
+                                                          ValueType type)
+  {
+    if (query_.get() != NULL)
+    {
+      query_->SetType(parameter, type);
+    }
+  }
+      
+      
+  void DatabaseManager::CachedStatement::Execute()
+  {
+    Dictionary parameters;
+    Execute(parameters);
+  }
+
+
+  void DatabaseManager::CachedStatement::Execute(const Dictionary& parameters)
+  {
+    if (result_.get() != NULL)
+    {
+      LOG(ERROR) << "Cannot execute twice a statement";
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+
+    try
+    {
+      if (query_.get() != NULL)
+      {
+        // Register the newly-created statement
+        assert(statement_ == NULL);
+        statement_ = &manager_.CacheStatement(location_, *query_);
+        query_.reset(NULL);
+      }
+        
+      assert(statement_ != NULL);
+      result_.reset(transaction_.Execute(*statement_, parameters));
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+
+
+  bool DatabaseManager::CachedStatement::IsDone() const
+  {
+    try
+    {
+      return GetResult().IsDone();
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+
+
+  void DatabaseManager::CachedStatement::Next()
+  {
+    try
+    {
+      GetResult().Next();
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+
+
+  size_t DatabaseManager::CachedStatement::GetResultFieldsCount() const
+  {
+    try
+    {
+      return GetResult().GetFieldsCount();
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+
+
+  void DatabaseManager::CachedStatement::SetResultFieldType(size_t field,
+                                                            ValueType type)
+  {
+    try
+    {
+      if (!GetResult().IsDone())
+      {
+        GetResult().SetExpectedType(field, type);
+      }
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+
+
+  const IValue& DatabaseManager::CachedStatement::GetResultField(size_t index) const
+  {
+    try
+    {
+      return GetResult().GetField(index);
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      manager_.CloseIfUnavailable(e.GetErrorCode());
+      throw;
+    }
+  }
+}