copy-on-write

I've got the following function: func checkFiles(path string, excludedPatterns []string) { // ... } I'm wondering, since excludedPatterns never changes, should I optimize it by making the var global (and not passing it to the function every time), or does Golang already handle this by passing them as copy-on-write? Edit: I guess I could pass the slice as a pointer, but I'm still wondering about the copy-on-write behavior (if it exists) and whether, in general, I should worry about passing by value or by pointer. Judging from the name of your function, performance can't be that critical to even

I know that swift will optimize to copy on write for arrays but will it do this for all structs? For example: struct Point { var x:Float = 0 } var p1 = Point() var p2 = p1 //p1 and p2 share the same data under the hood p2.x += 1 //p2 now has its own copy of the data Hamish Array is implemented with copy-on-write behaviour – you'll get it regardless of any compiler optimisations (although of course, optimisations can decrease the number of cases where a copy needs to happen). At a basic level, Array is just a structure that holds a reference to a heap-allocated buffer containing the elements –

Here is my code int main() { pid_t pid; int y = 3; if ( (pid = fork()) <0 ) return -1;; if( pid == 0 ) /* child */ { printf(" before: %d %p\n", y, &y ); y *= 10; printf("after: %d %p\n", y, &y ); } else /* father */ { sleep(1); printf("father: %d %p\n" , y , &y ); } return 0; } The output of the program is like following: before: 3 ffbff440 after: 30 ffbff440 father: 3 ffbff440 My question is why is address of variable of child and parent same but the value different? paxdiablo Because it's a virtual address, not a physical one. Each process gets its own address space (for example, a 32-bit

I would like to know what copy-on-write is and what it is used for? The term 'copy-on-write array' is mentioned several times in the Sun JDK tutorials but I didn't understand what it meant. I was going to write up my own explanation but this Wikipedia article pretty much sums it up. Here is the basic concept: Copy-on-write (sometimes referred to as "COW") is an optimization strategy used in computer programming. The fundamental idea is that if multiple callers ask for resources which are initially indistinguishable, you can give them pointers to the same resource. This function can be