Synopse Open Source

I'm currently fighting against out of memory errors on an heavy-loaded Java server.

If only it had been implemented in Delphi and mORMot!
But at this time, the mORMot was still in its burrow.
Copy-On-Write and a good heap manager can do wonders of stability.

Here are some thoughts about Garbage Collector, and how to temper their limitations.
They may apply to both the JVM and the .Net runtime, by the way.

On the Embarcadero forums, some user did have a perfectly sane reaction, about a non obvious integer type cast like Int64Var := Int32Var*Int32Var, which may overflow.

We've got to stop becoming, as one poster put it, "human pre-compilers" for Delphi.
The compiler ought to have the common sense to not need the programmer to cast the two integer values.

I respectfully think just the opposite.
;)

Such a type cast is part of the language grammar.
If you know the grammar, you will know how it will be compiled.

To be honest, you have the same in all languages, with more or less range checking, optimization, and implicit conversion.
This is why I like Delphi: it can be mastered by any programmers, whereas truly mastering Java or .Net needs a genius.

Delphi is just... human...

With upcoming revision 1.18 of the framework, our SynSQlite3.pas unit is able to access the SQLite3 engine in two ways:

• Either statically linked within the project executable;
• Or from an external sqlite3.dll library file.

The SQLite3 APIs and constants are defined in SynSQlite3.pas, and accessible via a TSQLite3Library class definition. It defines a global sqlite3 variable as such:

var
  sqlite3: TSQLite3Library;

To use the SQLite3 engine, an instance of TSQLite3Library class shall be assigned to this global variable. Then all mORMot's calls will be made through it, calling e.g. sqlite3.open() instead of sqlite3_open().

There are two implementation classes:

Referring to SynSQLite3Static.pas in the uses clause of your project is enough to link the .obj engine into your executable.

Warning - breaking change: before version 1.18 of the framework, link of static .obj was forced - so you must add a reference to SynSQLite3Static in your project uses clause to work as expected.

In order to use an external sqlite3.dll library, you have to set the global sqlite3 variable as such:

 FreeAndNil(sqlite3); // release any previous instance (e.g. static)
 sqlite3 := TSQLite3LibraryDynamic.Create;

Of course, FreeAndNil(sqlite3) is not mandatory, and should be necessary only to avoid any memory leak if another SQLite3 engine instance was allocated (may be the case if SynSQLite3Static is referred somewhere in your project's units).

Here are some benchmarks, compiled with Delphi XE3, run in a 32 bit project, using either the static bcc-compiled engine, or an external sqlite3.dll, compiled via MinGW or Microsoft Visual C++.