2020-09-09

Data Alignment and Delphi 10.4.1

Some regression has been reported with Delphi 10.4.1 and SynPDF.

From the Github issue description: Generating a PDF via VLCCanvas and TPdfDocumentGDI causes access violation when compiled with Delphi 10.4.1 with record field alignment compiler option set to "byte" or "off". When this option is set to either of "word", "double word" or "quad word", the PDF gets created without errors. The same exact code works fine when compiled with Delphi 10.4 (patch 3), regardless of the field alignment flag.

Sadly, I don't have access to Delphi 10.4.1 since I don't have any commercial licence, and I am waiting for the Community Edition - which is still 10.3 IIRC. So I couldn't debug the root cause and fill a JIRA ticket to EMB. We tried to add a {$A+} at the beginning of the unit, to force the default record alignment. And it seemed to work. So we included the directive for all of our units, in the shared Synopse.inc file, which is included in every of our source code units.

This blog entry is mainly to notify about this issue, and be able to share the solution/workaround we found, which could be investigated more deeply by Delphi users of the 10.4.1 revision. I guess that this problem may occur for other projects, when calling raw API.

Maybe it was a righteous fix introduced in 10.4.1, and the previous behavior of the compiler may have been incorrect: perhaps an explicit {$A+} is required when working with records... but at least, it breaks existing code, so spreading the info may help...

So feedback is welcome in our forum, if you wish to!

Update:

It sounds definitively like a bug/regression of 10.4.1. Reported initially as RSP-30787 and more specifically RSP-30890. Thanks François and Stefan for the good investigation in Delphi Praxis!

To be honest, setting an alignment to "byte" for a whole project is a pretty weird idea, and should never be done in practice. Default alignment is good for performance and compatibility. If you need no alignment for a record or a class, just use {$A-} ...{$A+} locally.

2020-08-11

The RFC, The URI, and The Tilde

For several reasons, only plain ASCII characters are accepted in Web URIs. Other characters should be escaped with % and the hexadecimal value of its code.

The tilde character ~ is not needed to be escaped... at least in theory... because in practice most code expects it...

A journey into confusing RFCs...

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2020-07-20

Special Care of Delphi 10.4

sillybug.jpg, Jul 2020

A regression in the Delphi 10.4 compiler was identified. Its optimizer wrongly deletes some code, in one very specific part of the framework.

sillybug.jpg, Jul 2020

As a result a GPF (Access violation) may be triggered with Delphi 10.4 in release mode - the debug mode (when optimization is disabled) has no problem. Thanks to great user feedback, we were able to circumvent it. But we should better stay in alert, like any mORMot, until Delphi 10.4 officially release a patch.

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2020-07-02

mORMot on GitHub Sponsors

We just enrolled on GitHub Sponsors!

Aim is to allow proper evolution of our Open Source project, especially the upcoming mORMot2.

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2020-06-05

SQlite3 Encryption Not Possible Any More Since 3.32.x

About latest SQlite3 3.32.xxx there is a big problem with codecs.

Critical changes to the public SQLite code were introduced on Feb 7, 2020: “Simplify the code by removing the unsupported and undocumented SQLITE_HAS_CODEC compile-time option”. With the release of SQLite version 3.32.0 on May 22, 2020 these changes finally took officially effect, although they weren't officially announced.

As a sad and unexpected consequence, we are NOT ANY MORE able to compile the new SQlite3 amalgamation with our encryption patch.

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2020-05-07

New Multi-thread Friendly Memory Manager for FPC written in x86_64 assembly

As a gift to the FPC community, I just committed a new Memory Manager for FPC.
Check mormot.core.fpcx64mm.pas in our mORMot2 repository.
This is a stand-alone unit for FPC only.

It targets Windows and Linux multi-threaded Service applications - typically mORMot daemons.
It is written in almost pure x86_64 assembly, and some unique tricks in the Delphi/FPC Memory Manager world.

It is based on FastMM4 (not FastMM5), and we didn't follow the path of the FastMM4-AVX version - instead of AVX, we use plain good (non-temporal) SSE2 opcode, and we rely on the mremap API on Linux for very efficient reallocation. Using mremap is perhaps the biggest  benefit of this memory manager - it leverages a killer feature of the Linux kernel for sure. By the way, we directly call the Kernel without the need of the libc.

We tuned our x86_64 assembly a lot, and made it cross-platform (Windows and POSIX). We profiled the multi-threading, especially by adding some additional small blocks for GetMem (which is a less expensive notion of "arenas" as used in FastMM5 and most C allocators), introducing an innovatice and very efficient round-robin of tiny blocks (<128 bytes), and proper spinning for FreeMem and medium blocks.

It runs all our regression tests with huge performance and stability - including multi-threaded tests with almost no slow down: sleep is reported as less than 1 ms during a 1 minute test. It has also been validated on some demanding multi-threaded tasks.

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2020-03-30

Debriefing of mORMot2 Survey

Thanks you all for have posted your feedback on our mORMot2 Survey!

Here are some insights.

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2020-03-28

Faster Double-To-Text Conversion

On server side, a lot of CPU is done processing conversions to or from text. Mainly JSON these days.

In mORMot, we take care a lot about performance, so we have rewritten most conversion functions to have something faster than the Delphi or FPC RTL can offer.
Only float to text conversion was not available. And RTL str/floattexttext performance, at least under Delphi, is not consistent among platforms.
So we just added a new Double-To-Text set of functions.

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2020-03-06

We Need U: Survey about mORMot 2.0

First of all, if it was not clear enough: Delphi will continue to be supported in mORMot 2.0. Some people reported that our previous article may have been misleading. But perhaps not all versions. For sure, Delphi 5 and Kylix will not be supported in mORMot 2. It is also possible that it would not  […]

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2020-03-03

Preparing Revision 2.x of the mORMot Framework

The more I think of it, the more I am convinced it is time to change how the framework is versioned.
We have version 1.18 since years... difficult to follow... time to upgrade!


I would like to upgrade mORMot to version 2 - with a major refactoring.

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2020-02-17

New move/fillchar optimized sse2/avx asm version

Our Open Source framework includes some optimized asm alternatives to RTL's move() and fillchar(), named MoveFast() and FillCharFast().

We just rewrote from scratch the x86_64 version of those, which was previously taken from third-party snippets.
The brand new code is meant to be more efficient and maintainable. In particular, we switched to SIMD 128-bit SSE2 or 256bit AVX memory access (if available), whereas current version was using 64-bit regular registers. The small blocks (i.e. < 32 bytes) process occurs very often, e.g. when processing strings, so has been tuned a lot. Non temporal instructions (i.e. bypassing the CPU cache) are used for biggest chunks of data. We tested ERMS support, but it was found of no benefit in respect to our optimized SIMD, and was actually slower than our non-temporal variants. So ERMS code is currently disabled in the source, and may be enabled on demand by a conditional.

FPC move() was not bad. Delphi's Win64 was far from optimized - even ERMS was poorly introduced in latest RTL, since it should be triggered only for blocks > 2KB. Sadly, Delphi doesn't support AVX assembly yet, so those opcodes would be available only on FPC.

Resulting numbers are talking by themselves. Working on Win64 and Linux, of course.

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2019-12-25

Merry Christmas and Happy New Year!

Let the little mORMot wish you and all yours a merry Christmas and a happy New Year! Happy coding!

2019-10-30

EKON 23 Presentation Slides and Code

I just finished my workshop at EKON 23.
Like every year, it was a great event to attempt to, and I enjoyed presenting 2 sessions and 1 workshop.

Sessions were about "Kingdom Driven Design" (KDD), which is the name I used to define a cut-down version of "Domain Driven Design" (DDD).
Less paranoid, a bit less isolation, but perhaps more common sense for the less sensitive projects.
Some presentations and code are now available!

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2019-10-17

Nice introductory articles about mORMot

I just found some very nice articles by Stephan Bester about first steps to mORMot's ORM and SOA.

Don't be scared by the mORMot: it is more stressed than you are.
This painful picture just won a wildlife photographer prize... poor little rodent!

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2019-09-21

SQLite3 static linking for Delphi Win64

A long-awaited feature was the ability to create stand-alone mORMot Win64 applications via Delphi, with no external sqlite3-64.dll required.

It is now available, with proper integration, and encryption is working!

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2019-09-18

Introducing Kingdom Driven Design at EKON 23

There are still some days to join EKON 23 conferences with the reduced price!

I will make 2 sessions, and 1 workshop, in English (my German is not good enough), about practical project design and mORMot.
If you find DDD is a bit too much for you, but still want to write clean code, check this!

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2018-11-24

mORMot running on Delphi 10.3 Rio

Now that Delphi 10.3 Rio is out, we had to ensure that our little mORMot would run with this revision. Since we don't make any commercial software with Delphi any more (we switched to FPC), I downloaded the Community Edition. We disabled the Error Insight feature, which seems not very stable  […]

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2018-11-12

Win 100GB of log space from a Real Life mORMot Project

Sometimes, I am asked what could be done with mORMot. Well, we've been using the library at LiveMon to analyse logs for example. And we're able to get speed of a few TB/sec. Speed above is no typo: TB/s not GB/s. For a regex search, not a per-word dictionary based lookup. With a cross-platform  […]

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EKON 22 Slides and Code

I've uploaded two sets of slides from my presentations at EKON 22 : Object Pascal Clean Code Guidelines Proposal High Performance Object Pascal Code on Servers with the associated source code The WorkShop about "Getting REST with mORMot" has a corresponding new Samples folder in our  […]

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2018-03-12

New AES-based SQLite3 encryption

We just committed a deep refactoring of the SynSQlite3Static.pas unit - and all units using static linking for FPC. It also includes a new encryption format for SQlite3, using AES, so much more secure than the previous one. This is a breaking change, so worth a blog article! Now all static .o .a  […]

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