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feat(sidecar)!: Add stats computation via SHM #1821

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feat(sidecar)!: Add stats computation via SHM #1821

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e00c9d6
Add stats computation via SHM
bwoebi Mar 30, 2026
e0ea995
clippy
bwoebi Mar 30, 2026
21b7ed7
PR comments
bwoebi Mar 31, 2026
a102d48
Fix ftruncate() causing SIGBUS on /dev/shm full
bwoebi Apr 9, 2026
db03e5c
Add tag filters to /info
bwoebi Apr 10, 2026
d4cde3e
Fixup after rebase
bwoebi Apr 10, 2026
67e6d3a
Actually reuse the exporter
bwoebi Apr 10, 2026
1837fb9
fix compile
bwoebi Apr 13, 2026
9e69e0f
Stats exporter in README
bwoebi Apr 13, 2026
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2 changes: 1 addition & 1 deletion .github/workflows/lint.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ jobs:
export AWS_LC_FIPS_SYS_NO_ASM=1
fi
# shellcheck disable=SC2046
cargo clippy --workspace --all-targets --all-features -- -D warnings
cargo clippy --workspace --all-targets --all-features -- -D warnings $([ ${{ matrix.rust_version }} = 1.84.1 ] || echo -Aclippy::manual_is_multiple_of)
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@VianneyRuhlmann VianneyRuhlmann Apr 13, 2026

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I don't have a strong opinion but this should probably be discussed in #libdatadog

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@bwoebi bwoebi Apr 13, 2026

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We've done that in the past already for cases where our MSRV did not support APIs which became the only solution to satisfy a clippy lint in future. It misses a comment though, when we'll be able to drop this.

licensecheck:
runs-on: ubuntu-latest
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27 changes: 24 additions & 3 deletions Cargo.lock
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4 changes: 4 additions & 0 deletions datadog-ipc/Cargo.toml
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Expand Up @@ -8,6 +8,7 @@ publish = false

[dependencies]
anyhow = { version = "1.0" }
zwohash = "0.1.2"
bincode = { version = "1" }
futures = { version = "0.3", default-features = false }
io-lifetimes = { version = "1.0" }
Expand All @@ -19,6 +20,9 @@ libdd-tinybytes = { path = "../libdd-tinybytes", optional = true }


libdd-common = { path = "../libdd-common" }
libdd-ddsketch = { path = "../libdd-ddsketch" }
libdd-trace-protobuf = { path = "../libdd-trace-protobuf" }
libdd-trace-stats = { path = "../libdd-trace-stats" }
datadog-ipc-macros = { path = "../datadog-ipc-macros" }
tracing = { version = "0.1", default-features = false }

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1 change: 1 addition & 0 deletions datadog-ipc/src/lib.rs
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Expand Up @@ -12,6 +12,7 @@ pub mod handles;

pub mod platform;
pub mod rate_limiter;
pub mod shm_stats;

pub mod client;
pub mod codec;
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17 changes: 14 additions & 3 deletions datadog-ipc/src/platform/mem_handle.rs
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Expand Up @@ -6,6 +6,8 @@ use crate::platform::{mmap_handle, munmap_handle, OwnedFileHandle, PlatformHandl
#[cfg(feature = "tiny-bytes")]
use libdd_tinybytes::UnderlyingBytes;
use serde::{Deserialize, Serialize};
#[cfg(target_os = "linux")]
use std::os::fd::AsRawFd;
use std::{ffi::CString, io, ptr::NonNull};

#[derive(Clone, Serialize, Deserialize, Debug)]
Expand Down Expand Up @@ -87,10 +89,19 @@ where
unsafe {
self.set_mapping_size(size)?;
}
nix::unistd::ftruncate(
self.get_shm().handle.as_owned_fd()?,
self.get_shm().size as libc::off_t,
let new_size = self.get_shm().size as libc::off_t;
let fd = self.get_shm().handle.as_owned_fd()?;
// Use fallocate on Linux to eagerly commit the new pages: ENOSPC at resize time is
// recoverable; a later SIGBUS mid-execution is not.
#[cfg(target_os = "linux")]
nix::fcntl::fallocate(
fd.as_raw_fd(),
nix::fcntl::FallocateFlags::empty(),
0,
new_size,
)?;
#[cfg(not(target_os = "linux"))]
nix::unistd::ftruncate(&fd, new_size)?;
Ok(())
}
/// # Safety
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7 changes: 7 additions & 0 deletions datadog-ipc/src/platform/unix/mem_handle.rs
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Expand Up @@ -7,6 +7,8 @@ use crate::platform::{
use io_lifetimes::OwnedFd;
use libc::{chmod, off_t};
use nix::errno::Errno;
#[cfg(target_os = "linux")]
use nix::fcntl::{fallocate, FallocateFlags};
use nix::fcntl::{open, OFlag};
use nix::sys::mman::{self, mmap, munmap, MapFlags, ProtFlags};
use nix::sys::stat::Mode;
Expand Down Expand Up @@ -163,6 +165,11 @@ impl NamedShmHandle {

pub fn create_mode(path: CString, size: usize, mode: Mode) -> io::Result<NamedShmHandle> {
let fd = shm_open(path.as_bytes(), OFlag::O_CREAT | OFlag::O_RDWR, mode)?;
// Use fallocate on Linux to eagerly commit pages: if /dev/shm is full we get ENOSPC
// here (recoverable) rather than SIGBUS mid-execution when a worker writes a slot.
#[cfg(target_os = "linux")]
fallocate(fd.as_raw_fd(), FallocateFlags::empty(), 0, size as off_t)?;
#[cfg(not(target_os = "linux"))]
ftruncate(&fd, size as off_t)?;
if let Some(uid) = shm_owner_uid() {
let _ = fchown(fd.as_raw_fd(), Some(Uid::from_raw(uid)), None);
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2 changes: 1 addition & 1 deletion datadog-ipc/src/platform/unix/mem_handle_macos.rs
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Expand Up @@ -17,7 +17,7 @@ use std::os::fd::{AsFd, OwnedFd};
use std::os::unix::io::AsRawFd;
use std::sync::atomic::{AtomicI32, AtomicU32, AtomicUsize, Ordering};

const MAPPING_MAX_SIZE: usize = 1 << 17; // 128 MiB ought to be enough for everybody?
const MAPPING_MAX_SIZE: usize = 1 << 27; // 128 MiB ought to be enough for everybody?
const NOT_COMMITTED: usize = 1 << (usize::BITS - 1);

pub(crate) fn mmap_handle<T: FileBackedHandle>(mut handle: T) -> io::Result<MappedMem<T>> {
Expand Down
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