Timeline

[r1viollet]

Description

Allow timestamps to be added to the samples as labels.

Additional information

I added the process name as a label as it makes it easier to de-duplicate, rather than using the frame information.
We can re-visit this idea.

[datadog-datadog-prod-us1]

🟠 Code Vulnerability

Potential memory range aliasing. Avoid using the memory reference. (...read more)

Implicit memory aliasing in for loops refers to a scenario in Go programming when two or more pointers reference the same location in memory, creating unexpected side effects. This often results in a common mistake amongst Go programmers due to the 'range' clause.

Consider this example, where a slice of pointers is created in a loop:

data := []int{1, 2, 3}
pointers := make([]*int, 3)
for i, v := range data {
    pointers[i] = &v
}

You might expect the 'pointers' slice to hold addresses of elements in 'data' slice, but that's not the case. In each iteration of the loop, variable 'v' gets a new value but its memory address doesn't change because it's a loop variable. As a result, each element in 'pointers' slice points to the same memory location - the address of the loop variable 'v'. The final value of 'v' is '3', and since all pointers point to 'v', dereferencing the pointers would yield '3' regardless of the pointer's index in the slice.

To avoid implicit memory aliasing in for loops in Go, you should address the actual elements in the original data structure, like so:

data := []int{1, 2, 3}
pointers := make([]*int, 3)
for i := range data {
    pointers[i] = &data[i]
}

In this example, each pointer in the 'pointers' slice correctly points to the respective element in the 'data' slice.

Learn More

• StackOverflow: Implicit memory aliasing in for loop

    

[r1viollet]

I will silence this if we agree it is not an issue.

[Gandem]

I think this is not an issue thanks to https://go.dev/blog/loopvar-preview, and since go.mod has 1.22+ as the version https://github.com/DataDog/otel-profiling-agent/blob/main/go.mod#L3 this should be alright

[r1viollet]

I changed the traceAndMetaKey to a pointer, highlighting in case there was any thought put into this earlier

[Gandem]

I initially kept it as a variable to avoid having to deal with #55 (comment) since this code is not on the hot path anyway for the copy to be too expensive (only called once per minute). Also wanted to keep the code closer to the upstream OTLP reporter. But this works for me as well, no strong opinions 👍

[nsavoire]

🤓 nitpick: ‏ This does not seem to belong to the proposed change.

[datadog-datadog-prod-us1]

🟠 Code Vulnerability

Potential memory range aliasing. Avoid using the memory reference. (...read more)

Implicit memory aliasing in for loops refers to a scenario in Go programming when two or more pointers reference the same location in memory, creating unexpected side effects. This often results in a common mistake amongst Go programmers due to the 'range' clause.

Consider this example, where a slice of pointers is created in a loop:

data := []int{1, 2, 3}
pointers := make([]*int, 3)
for i, v := range data {
    pointers[i] = &v
}

You might expect the 'pointers' slice to hold addresses of elements in 'data' slice, but that's not the case. In each iteration of the loop, variable 'v' gets a new value but its memory address doesn't change because it's a loop variable. As a result, each element in 'pointers' slice points to the same memory location - the address of the loop variable 'v'. The final value of 'v' is '3', and since all pointers point to 'v', dereferencing the pointers would yield '3' regardless of the pointer's index in the slice.

To avoid implicit memory aliasing in for loops in Go, you should address the actual elements in the original data structure, like so:

data := []int{1, 2, 3}
pointers := make([]*int, 3)
for i := range data {
    pointers[i] = &data[i]
}

In this example, each pointer in the 'pointers' slice correctly points to the respective element in the 'data' slice.

Learn More

• StackOverflow: Implicit memory aliasing in for loop