- The power of lazy programming - 1 Update
- About memory safety and more.. - 1 Update
| aminer68@gmail.com: Dec 06 03:39PM -0800 Hello, The power of lazy programming These 13 tools and techniques prove that, when it comes to coding, laziness is a virtue Read more here: https://www.infoworld.com/article/3122803/the-power-of-lazy-programming.html Thank you, Amine Moulay Ramdane. |
| aminer68@gmail.com: Dec 06 11:44AM -0800 Hello, About memory safety and more.. I have just read the following webpage about memory safety: Microsoft: 70 percent of all security bugs are memory safety issues https://www.zdnet.com/article/microsoft-70-percent-of-all-security-bugs-are-memory-safety-issues/ And it says: "Users who often read vulnerability reports come across terms over and over again. Terms like buffer overflow, race condition, page fault, null pointer, stack exhaustion, heap exhaustion/corruption, use after free, or double free --all describe memory safety vulnerabilities." So as you will notice below, that the following memory safety problems has been solved in Delphi: And I have just read the following webpage about "Fearless Security: Memory safety": https://hacks.mozilla.org/2019/01/fearless-security-memory-safety/ Here is the memory safety problems: 1- Misusing Free (use-after-free, double free) I have solved this in Delphi and Freepascal by inventing a "Scalable" reference counting with efficient support for weak references. Read below about it. 2- Uninitialized variables This can be detected by the compilers of Delphi and Freepascal. 3- Dereferencing Null pointers I have solved this in Delphi and Freepascal by inventing a "Scalable" reference counting with efficient support for weak references. Read below about it. 4- Buffer overflow and underflow This has been solved in Delphi by using madExcept, read here about it: http://help.madshi.net/DebugMm.htm You can buy it from here: http://www.madshi.net/ There remains also the stack exhaustion memory safety problem, and here is how to detect it in Delphi: Call the function "DoStackOverflow" below once from your code and you'll get the EStackOverflow error raised by Delphi with the message "stack overflow", and you can print the line of the source code where EStackOverflow is raised with JCLDebug and such: ---- function DoStackOverflow : integer; begin result := 1 + DoStackOverflow; end; --- About my scalable algorithms inventions.. I am a white arab, and i am a gentleman type of person, and i think that you know me too by my poetry that i wrote in front of you and that i posted here, but i am also a more serious computer developer, and i am also an inventor who has invented many scalable algorithms, read about them on my writing below: Here is my last scalable algorithm invention, read what i have just responded in comp.programming.threads: About my LRU scalable algorithm.. On 10/16/2019 7:48 AM, Bonita Montero on comp.programming.threads wrote: > in locked mode in very rare cases. And as I said inserting and > flushing is conventional locked access. > So the quest is for you: Can you guess what I did? And here is what i have just responded: I think i am also smart, so i have just quickly found a solution that is scalable and that is not your solution, so it needs my hashtable that is scalable and it needs my fully scalable FIFO queue that i have invented. And i think i will not patent it. But my solution is not Lockfree, it uses locks like in a Lock striping manner and it is scalable. And read about my other scalable algorithms inventions on my writing below: About the buffer overflow problem.. I wrote yesterday about buffer overflow in Delphi and Freepascal.. I think there is a "higher" abstraction in Delphi and Freepascal that does the job very well of avoiding buffer overflow, and it is the TMemoryStream class, since it behaves also like a pointer and it supports reallocmem() and freemem() on the pointer but with a higher level abstraction, look for example at my following example in Delphi and Freepascal, you will notice that contrary to pointers , that the memory stream is adapting with writebuffer() without the need of reserving the memory, and this is why it avoids the buffer overflow problem, read the following example to notice how i am using it with a PAnsichar type: ======================================== Program test; uses system.classes,system.sysutils; var P: PAnsiChar; Begin P:='Amine'; mem:=TMemorystream.create; mem.position:=0; mem.writebuffer(pointer(p)^,6); mem.position:=0; writeln(PAnsichar(mem.memory)); end. =================================== So since Delphi and Freepascal also detect the buffer overflow on dynamic arrays , so i think that Delphi and Freepascal are powerful tools. Read my previous thoughts below to understand more: And I have just read the following webpage about "Fearless Security: Memory safety": https://hacks.mozilla.org/2019/01/fearless-security-memory-safety/ Here is the memory safety problems: 1- Misusing Free (use-after-free, double free) I have solved this in Delphi and Freepascal by inventing a "Scalable" reference counting with efficient support for weak references. Read below about it. 2- Uninitialized variables This can be detected by the compilers of Delphi and Freepascal. 3- Dereferencing Null pointers I have solved this in Delphi and Freepascal by inventing a "Scalable" reference counting with efficient support for weak references. Read below about it. 4- Buffer overflow and underflow This has been solved in Delphi by using madExcept, read here about it: http://help.madshi.net/DebugMm.htm You can buy it from here: http://www.madshi.net/ And about race conditions and deadlocks problems and more, read my following thoughts to understand: I will reformulate more smartly what about race conditions detection in Rust, so read it carefully: You can think of the borrow checker of Rust as a validator for a locking system: immutable references are shared read locks and mutable references are exclusive write locks. Under this mental model, accessing data via two independent write locks is not a safe thing to do, and modifying data via a write lock while there are readers alive is not safe either. So as you are noticing that the "mutable" references in Rust follow the Read-Write Lock pattern, so this is not good, because it is not like more fine-grained parallelism that permits us to run the writes in "parallel" and gain more performance from parallelizing the writes. Read more about Rust and Delphi and my inventions.. I think the spirit of Rust is like the spirit of ADA, they are especially designed for the very high standards of safety, like those of ADA, "but" i don't think we have to fear race conditions that Rust solve, because i think that race conditions are not so difficult to avoid when you are a decent knowledgeable programmer in parallel programming, so you have to understand what i mean, now we have to talk about the rest of the safety guaranties of Rust, there remain the problem of Deadlocks, and i think that Rust is not solving this problem, but i have provided you with an enhanced DelphiConcurrent library for Delphi and Freepascal that detects deadlocks, and there is also the Memory Safety guaranties of Rust, here they are: 1- No Null Pointer Dereferences 2- No Dangling Pointers 3- No Buffer Overruns But notice that I have solved the number 1 and number 2 by inventing my scalable reference counting with efficient support for weak references for Delphi and Freepascal, read below to notice it, and for number 3 read my following thoughts to understand: More about research and software development.. I have just looked at the following new video: Why is coding so hard... https://www.youtube.com/watch?v=TAAXwrgd1U8 I am understanding this video, but i have to explain my work: I am not like this techlead in the video above, because i am also an "inventor" that has invented many scalable algorithms and there implementions, i am also inventing effective abstractions, i give you an example: Read the following of the senior research scientist that is called Dave Dice: Preemption tolerant MCS locks https://blogs.oracle.com/dave/preemption-tolerant-mcs-locks As you are noticing he is trying to invent a new lock that is preemption tolerant, but his lock lacks some important characteristics, this is why i have just invented a new Fast Mutex that is adaptative and that is much much better and i think mine is the "best", and i think you will not find it anywhere, my new Fast Mutex has the following characteristics: 1- Starvation-free 2- Good fairness 3- It keeps efficiently and very low the cache coherence traffic 4- Very good fast path performance (it has the same performance as the scalable MCS lock when there is contention.) 5- And it has a decent preemption tolerance. this is how i am an "inventor", and i have also invented other scalable algorithms such as a scalable reference counting with efficient support for weak references, and i have invented a fully scalable Threadpool, and i have also invented a Fully scalable FIFO queue, and i have also invented other scalable algorithms and there inmplementations, and i think i will sell some of them to Microsoft or to Google or Embarcadero or such software companies. Read my following writing to know me more: More about computing and parallel computing.. The important guaranties of Memory Safety in Rust are: 1- No Null Pointer Dereferences 2- No Dangling Pointers 3- No Buffer Overruns I think i have solved Null Pointer Dereferences and also solved Dangling Pointers and also solved memory leaks for Delphi and Freepascal by inventing my "scalable" reference counting with efficient support for weak references and i have implemented it in Delphi and Freepascal (Read about it below), and reference counting in Rust and C++ is "not" scalable. About the (3) above that is Buffer Overruns, read here about Delphi and Freepascal: What's a buffer overflow and how to avoid it in Delphi? read my above thoughts about it. About Deadlock and Race conditions in Delphi and Freepascal: I have ported DelphiConcurrent to Freepascal, and i have also extended them with the support of my scalable RWLocks for Windows and Linux and with the support of my scalable lock called MLock for Windows and Linux and i have also added the support for a Mutex for Windows and Linux, please look inside the DelphiConcurrent.pas and FreepascalConcurrent.pas files inside the zip file to understand more. You can download DelphiConcurrent and FreepascalConcurrent for Delphi and Freepascal from: https://sites.google.com/site/scalable68/delphiconcurrent-and-freepascalconcurrent DelphiConcurrent and FreepascalConcurrent by Moualek Adlene is a new way to build Delphi applications which involve parallel executed code based on threads like application servers. DelphiConcurrent provides to the programmers the internal mechanisms to write safer multi-thread code while taking a special care of performance and genericity. In concurrent applications a DEADLOCK may occurs when two threads or more try to lock two consecutive shared resources or more but in a different order. With DelphiConcurrent and FreepascalConcurrent, a DEADLOCK is detected and automatically skipped - before he occurs - and the programmer has an explicit exception describing the multi-thread problem instead of a blocking DEADLOCK which freeze the application with no output log (and perhaps also the linked clients sessions if we talk about an application server). Amine Moulay Ramdane has extended them with the support of his scalable RWLocks for Windows and Linux and with the support of his scalable lock called MLock for Windows and Linux and he has also added the support for a Mutex for Windows and Linux, please look inside the DelphiConcurrent.pas and FreepascalConcurrent.pas files to understand more. And please read the html file inside to learn more how to use it. About race conditions now: My scalable Adder is here.. As you have noticed i have just posted previously my modified versions of DelphiConcurrent and FreepascalConcurrent to deal with deadlocks in parallel programs. But i have just read the following about how to avoid race conditions in Parallel programming in most cases.. Here it is: https://vitaliburkov.wordpress.com/2011/10/28/parallel-programming-with-delphi-part-ii-resolving-race-conditions/ This is why i have invented my following powerful scalable Adder to help you do the same as the above, please take a look at its source code to understand more, here it is: https://sites.google.com/site/scalable68/scalable-adder-for-delphi-and-freepascal Other than that, about composability of lock-based systems now: Design your systems to be composable. Among the more galling claims of the detractors of lock-based systems is the notion that they are somehow uncomposable: "Locks and condition variables do not support modular programming," reads one typically brazen claim, "building large programs by gluing together smaller programs[:] locks make this impossible."9 The claim, of course, is incorrect. For evidence one need only point at the composition of lock-based systems such as databases and operating systems into larger systems that remain entirely unaware of lower-level locking. There are two ways to make lock-based systems completely composable, and each has its own place. First (and most obviously), one can make locking entirely internal to the subsystem. For example, in concurrent operating systems, control never returns to user level with in-kernel locks held; the locks used to implement the system itself are entirely behind the system call interface that constitutes the interface to the system. More generally, this model can work whenever a crisp interface exists between software components: as long as control flow is never returned to the caller with locks held, the subsystem will remain composable. Second (and perhaps counterintuitively), one can achieve concurrency and composability by having no locks whatsoever. In this case, there must be no global subsystem state—subsystem state must be captured in per-instance state, and it must be up to consumers of the subsystem to assure that they do not access their instance in parallel. By leaving locking up to the client of the subsystem, the subsystem itself can be used concurrently by different subsystems and in different contexts. A concrete example of this is the AVL tree implementation used extensively in the Solaris kernel. As with any balanced binary tree, the implementation is sufficiently complex to merit componentization, but by not having any global state, the implementation may be used concurrently by disjoint subsystems—the only constraint is that manipulation of a single AVL tree instance must be serialized. Read more here: https://queue.acm.org/detail.cfm?id=1454462 And about Message Passing Process Communication Model and Shared Memory Process Communication Model: An advantage of shared memory model is that memory communication is faster as compared to the message passing model on the same machine. Read the following to notice it: Why did Windows NT move away from the microkernel? "The main reason that Windows NT became a hybrid kernel is speed. A microkernel-based system puts only the bare minimum system components in the kernel and runs the rest of them as user mode processes, known as servers. A form of inter-process communication (IPC), usually message passing, is used for communication between servers and the kernel. Microkernel-based systems are more stable than others; if a server crashes, it can be restarted without affecting the entire system, which couldn't be done if every system component was part of the kernel. However, because of the overhead incurred by IPC and context-switching, microkernels are slower than traditional kernels. Due to the performance costs of a microkernel, |
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