Rust is not hard #1 | Highlights and Annotations by Gistr.

Intro when rust is released, there is a lots of languages already there, but there were problems which rust can solve, which made rust outstanding and most lovable to programmers. rust put forwards some new concepts to solves issues in the languages already in the market. Problem 1 : Memory Safety Allocating strings, numbers, arrays, etc., in memory (as variables or constants) is common in all programming languages. When these variables are no longer needed, their memory should be cleared. When memory is allocated or freed, several bugs can occur, such as: Buffer overflows/underflows Use-after-free Dangling pointers Double frees Uninitialized memory access 🧠 Memory Safety in Different Languages 🔹 C / C++: Not Memory Safe by Default C and C++ give programmers low-level control over memory, which is powerful but dangerous. They do not enforce memory safety by default , so it's up to the programmer to manage memory correctly. Java: Memory Safe Java enforces memory safety at both the language and runtime levels. Java ensures the memory safety by a program called Garbage Collector C/C++ we have more control over memory, and performant, but it's danger when come into memory safety, it cause to break programs. JAVA java handles memory but in a slower way, and without more controls over memory. Rust proposed another solution to ensure memory safety, which wouldnt' compromise performance . How Rust handles memory. Garbage Collection (Part 1) -- Introduction Garbage Collection: An Introduction This document provides structured notes on garbage collection, covering the fundamental concepts and introducing four basic types of garbage collection algorithms. Object References and Scope Key Concept: The lifetime of an object is tied to its references. If an object has no references pointing to it, it becomes unreachable and is considered "dead." ** Heap vs. Stack:** Objects allocated on the heap have an unbounded lifetime until explicitly deallocated or garbage collected. Local variables, on the other hand, follow scope rules; when they go out of scope, they are no longer accessible. Garbage Collection's Role: The primary function of a garbage collector is to identify and reclaim these dead, unreachable objects, freeing up memory for reuse. This prevents memory leaks. Mutator and Collector Threads: A garbage collection program typically involves two threads: Mutator Thread: This thread is responsible for the main program logic, modifying the object graph, allocating memory, and managing references. Collector Thread: This thread runs the garbage collection logic, identifying and reclaiming dead objects . This is often a separate thread to minimize interference with the main program's execution. Dead vs. Alive Objects Term Description Dead Object An object with no active references pointing to it. It's unreachable and occupies unnecessary memory. Alive Object An object that is currently referenced by at least one active reference. Garbage Collection Algorithms: A Preview The video introduces four fundamental garbage collection algorithms: Mark and Sweep: A common approach. Copying: Another widely used method. Mark and Compact: A variation aiming for efficiency. Reference Counting: A different approach with its own trade-offs. The subsequent sections will delve into the details of each algorithm, exploring their mechanisms and comparing their strengths and weaknesses. Summary and Key Takeaways This introduction established the foundational concepts of garbage collection, including the crucial relationship between object references and object lifecycles. The roles of the mutator and collector threads were clarified, setting the stage for a deeper exploration of specific garbage collection algorithms in subsequent sections. Understanding these concepts is essential for writing efficient and memory-safe programs. How rust forces you to respect memory Rust: Memory Management and Ownership This blog post summarizes a video explaining Rust's memory management approach and how it compares to C and Java. Rust offers a unique solution to memory leaks and the overhead of garbage collection, achieving the speed of C while enhancing memory safety. Memory Leaks in C In C, manually allocating and deallocating memory (using malloc and free ) is prone to errors . Forgetting to free allocated memory leads to memory leaks . This is a common issue, even for experienced developers. Example: Allocating 10 integers on the heap and failing to free them. Garbage Collection in Java Java uses a garbage collector to automatically manage memory. When an object is no longer referenced, the garbage collector reclaims its memory. Example: Allocating an array of 10 integers. When the reference variable goes out of scope, the garbage collector eventually frees the memory. However, garbage collection introduces overhead in terms of memory and CPU usage, and its non-deterministic nature can be problematic. Rust's Ownership System Rust introduces the concept of ownership to solve memory management issues without garbage collection. Each value has a single owner. When the owner goes out of scope, the value is automatically deallocated. Example : Allocating 10 integers on the heap. When the owning variable goes out of scope, the memory is freed immediately. This combines the speed of low-level languages like C with the memory safety benefits of higher-level languages. Ownership vs. Garbage Collection: A Deeper Look Feature C Java Rust Memory Management Manual Garbage Collection Ownership Speed Fast Slower (GC overhead) Fast Memory Safety Low Higher Very High Complexity High (prone to leaks) Moderate Higher (initially) Multiple References and the Move Operation In Java, multiple variables can reference the same data on the heap. The garbage collector only deallocates when all references are gone. Rust's move operation transfers ownership. When a variable's ownership is moved, the original variable becomes invalid. This prevents dangling pointers. Example: let r2 = r; moves ownership of the data from r to r2 . r is then invalid. Borrowing and References Rust's borrowing and referencing mechanisms allow sharing data without violating the ownership rule. This makes the system more flexible. These mechanisms are not detailed in this summary, but they are crucial for practical Rust programming. Summary and Key Takeaways Rust's ownership system provides a powerful alternative to manual memory management and garbage collection. It offers the speed of C while significantly improving memory safety and reducing the risk of memory leaks. While the initial learning curve might be steeper due to the ownership system, the long-term benefits in terms of code reliability and performance are substantial. Understanding concepts like borrowing and references is crucial for effectively utilizing Rust's memory management capabilities. This segment illustrates a common memory leak scenario in C, where forgetting to free allocated memory leads to wasted resources. It highlights the historical challenge of manual memory management in C and sets the stage for comparing it with other languages. This segment explains Java's garbage collection mechanism, contrasting it with C's manual memory management. It shows how Java automatically reclaims unused memory, preventing leaks but introducing overhead. This segment introduces Rust's ownership system as an alternative to both manual memory management (like in C) and garbage collection (like in Java). It explains the core concept of ownership where stack variables own heap data, automatically freeing memory when they go out of scope. This segment discusses the trade-offs involved in Rust's ownership system, emphasizing its ability to maintain the speed of low-level languages while improving memory management consistency and reducing the likelihood of bugs.This section compares how Java and Rust handle multiple references to the same heap data. It shows how Java's garbage collection safely manages this situation, while setting up the explanation of Rust's approach.This segment details Rust's "move" semantics, explaining how ownership is transferred between variables. It also introduces the concepts of borrowing and references, which mitigate the limitations of strict ownership while maintaining memory safety. rust fix the issue through ownership model . in a ownership model Each value has a single owner . When the owner goes out of scope, the value is automatically deallocated. let s1 = String::from("lisabi"); let s2 = s1; In rust a value should have one owner. so in the code above, when s1 is assigned to s2 , s1 is no longer there. Rust's ownership system and Java's garbage collection represent fundamentally different approaches to memory management. Java relies on a garbage collector, a background process that periodically identifies and reclaims memory no longer in use . This introduces overhead in terms of both memory and CPU usage, and its non-deterministic nature can lead to performance inconsistencies . In contrast, Rust employs an ownership system where each value on the stack explicitly "owns" its corresponding data on the heap . When an owning variable goes out of scope, the associated heap memory is automatically deallocated . This deterministic approach avoids memory leaks and provides performance predictability. However, Rust's strict ownership rules, while preventing memory leaks, can initially seem limiting . Java's garbage collection allows for more flexible memory management, enabling multiple variables to reference the same heap data without explicit ownership transfer . Rust mitigates this limitation through concepts like borrowing and references, allowing controlled sharing of data without violating ownership principles . The "move" operation in Rust explicitly transfers ownership, preventing dangling pointers . In Java, a garbage collector handles this implicitly, but at the cost of potential performance overhead. In essence, Rust prioritizes safety and deterministic performance through its ownership model, while Java prioritizes flexibility and ease of use with its garbage collection, accepting the potential performance trade-offs. Could you explain the concept of borrowing in Rust and how it relates to the ownership system?