perf!: reduce hot-path allocations in receipt, send, and signal paths by jlucaso1 · Pull Request #519 · oxidezap/whatsapp-rust

jlucaso1 · 2026-04-12T19:33:10Z

Summary

Receipt construction: move values instead of cloning — reduces from 6 clones to 1 per incoming receipt
Remove dead Receipt.message_sender: field duplicated source.sender and was never read
encode_and_pad(): replace pad_message_v2(msg.encode_to_vec()) with single pre-sized allocation in DM, group SKDM, and signal encrypt paths
Remove redundant clone: jid_to_encryption_jid.insert(jid, jid.clone()) was unnecessary — the encrypt loop already falls back to device_jid when no mapping exists
Remove unused import: prost::Message no longer needed in signal.rs

Breaking changes

Receipt.message_sender field removed (was never accessed, always duplicated source.sender)

Experiment data

From experiments/heaptrack-impact-lab (10k node benchmark):

Optimization	alloc delta	byte delta	time delta
Receipt: move vs clone	-100%	-100%	-72.4%
encode_and_pad vs encode_to_vec+pad	-99.9%	-98.5%	~neutral
Session map: skip self-mapping	+0%	+0%	-4.9%

Test plan

cargo fmt --all
cargo clippy --all --tests
cargo test --all --exclude e2e-tests

Summary by CodeRabbit

Breaking Changes
- Removed message_sender field from Receipt events. Code relying on this field requires updates.
Refactor
- Optimized message encryption plaintext preparation across direct and group messaging paths.
- Enhanced Receipt handling to eliminate redundant copying and improve memory efficiency.
- Removed unused code dependencies.

- Receipt: move values instead of cloning (6 clones → 1 per receipt) - Remove dead `Receipt.message_sender` field (duplicated `source.sender`) - Use `encode_and_pad()` instead of `pad_message_v2(encode_to_vec())` for single pre-sized allocation in DM, group SKDM, and signal paths - Remove redundant self-mapping clone in encrypt_for_devices - Remove unused prost import from signal.rs

coderabbitai · 2026-04-12T19:33:22Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 9f16c974-1217-4c1a-a41c-718f34ca2ed6

📥 Commits

Reviewing files that changed from the base of the PR and between 1007676 and 2f05e91.

📒 Files selected for processing (4)

src/features/signal.rs
src/receipt.rs
wacore/src/send.rs
wacore/src/types/events.rs

💤 Files with no reviewable changes (1)

wacore/src/types/events.rs

📝 Walkthrough

Walkthrough

This PR refactors message encryption handling and receipt type management across the codebase. Changes include replacing MessageUtils::pad_message_v2(message.encode_to_vec()) with MessageUtils::encode_and_pad(message) for more efficient plaintext preparation, removing redundant cloning in receipt construction to preserve ownership semantics, and removing the message_sender field from the public Receipt struct (a breaking change).

Changes

Cohort / File(s)	Summary
Message Encryption Refactoring `src/features/signal.rs`, `wacore/src/send.rs`	Replaced `MessageUtils::pad_message_v2(message.encode_to_vec())` calls with `MessageUtils::encode_and_pad(message)` for DSM and SKDM wrapper messages. Also removed a `jid_to_encryption_jid` insertion when a session already exists under the direct device address in `encrypt_for_devices`.
Receipt Type and Field Changes `src/receipt.rs`, `wacore/src/types/events.rs`	Refactored `handle_receipt` to use ownership-preserving patterns (moving values instead of cloning); removed public `message_sender: Jid` field from `Receipt` struct. Updated downstream receipt field references to use the constructed receipt object.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

#474: Modifies signal/message encryption codepaths with the same MessageUtils::pad_message_v2 to MessageUtils::encode_and_pad refactoring pattern.
#502: Applies similar encode-and-pad changes and ownership-preserving ciphertext serialization patterns across signal and send paths.
#362: Touches related messaging/receipt and send-path code with overlapping MessageUtils and Receipt type changes.

Suggested labels

breaking-change

Poem

🐰 Hops through plaintext with swiftened stride,
encode\_and\_pad now takes the ride,
Clones replaced with moves so clean,
Receipt fields trimmed, leaner seen!
Breaking change hops past with care,
Ownership patterns fill the air! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main focus of the changeset: performance optimization through allocation reduction in three key paths (receipt, send, and signal).
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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Commit unit tests in branch perf/hot-path-allocation-reduction

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jlucaso1 · 2026-04-12T19:33:35Z

@claude review

claude · 2026-04-12T19:33:52Z

Claude finished @jlucaso1's task in 1m 57s —— View job

Code Review: `perf!: reduce hot-path allocations`

Read changed files and diff
Analyze changes for correctness, safety, and style
Post review feedback

Verdict: Approve — clean, correct, and well-motivated changes. All four optimizations are sound. A couple of minor observations below, but nothing blocking.

1. Receipt construction — move semantics (`src/receipt.rs`)

The refactor from 6 clones to moves is correct. Key details verified:

is_group is computed from from.is_group() before from is moved into receipt.source.chat (line 49 vs 59) — good.
Post-move accesses (receipt.r#type, receipt.source.chat) correctly go through the struct — no use-after-move.
ReceiptType is Clone + PartialEq (not Copy), so the comparison receipt.r#type == ReceiptType::Retry borrows through the struct — correct.

One minor note: ReceiptType is a simple fieldless enum. It could derive Copy to avoid the borrow concern entirely, but that's outside this PR's scope and not a problem as-is.

2. `Receipt.message_sender` removal (`wacore/src/types/events.rs`)

Confirmed no references to Receipt.message_sender exist anywhere in the codebase — grep returns zero hits. The field was always a duplicate of source.sender. The breaking change callout in the PR description is appropriate since Receipt is a public struct with Serialize.

3. `encode_and_pad()` (`src/features/signal.rs`, `wacore/src/send.rs`)

The switch from pad_message_v2(msg.encode_to_vec()) to encode_and_pad(msg) eliminates a double allocation:

encode_to_vec() allocates a Vec, then pad_message_v2 resizes it (potentially reallocating if padding exceeds spare capacity).
encode_and_pad pre-sizes Vec::with_capacity(encoded_len + pad), encodes in-place, then resize is a no-op reallocation since capacity was pre-reserved.

All three call sites (signal encrypt, DM prepare_dm_stanza, group SKDM) are updated consistently.

The unused prost::Message import removal in signal.rs is correct — encode_to_vec() was the only thing requiring it.

4. Redundant self-mapping removal (`wacore/src/send.rs:405`)

The removed line was:

jid_to_encryption_jid.insert(device_jid, device_jid.clone());

Both consumers of jid_to_encryption_jid use .get(device_jid).unwrap_or(device_jid) (lines 483, 605), which already falls back to the device JID itself when no mapping exists — making the self-insert a no-op allocation. Verified that this branch (continue at line 406) means the device already has a session under its direct address and won't appear in jids_needing_prekeys, so the line 483 consumer is also unaffected. Correct removal.

The two removed comment lines (// Session exists under direct address, use it) matched the deleted logic — clean.

LGTM. Nice targeted perf wins with a small diff.

github-actions · 2026-04-12T19:38:36Z

Benchmark Results

59 unchanged benchmark(s)

Benchmark	Current	Baseline	Change
`reporting_token_benchmark::content_extraction_group::bench_content_extraction simple:setup_simple_message()`	3,879	3,879	+0.0%
`reporting_token_benchmark::content_extraction_group::bench_content_extraction extended:setup_extended_message()`	11,851	11,851	+0.0%
`reporting_token_benchmark::key_derivation_group::bench_key_derivation`	43,398	43,398	+0.0%
`reporting_token_benchmark::token_calculation_group::bench_token_calculation`	19,365	19,365	+0.0%
`reporting_token_benchmark::full_generation_group::bench_full_token_generation simple:setup_full_gen_simple()`	68,814	68,814	+0.0%
`reporting_token_benchmark::full_generation_group::bench_full_token_generation extended:setup_full_gen_extended()`	76,781	76,781	+0.0%
`reporting_token_benchmark::message_encoding_group::bench_message_encoding simple:setup_simple_message()`	2,214	2,214	+0.0%
`reporting_token_benchmark::message_encoding_group::bench_message_encoding extended:setup_extended_message()`	5,939	5,939	+0.0%
`send_receive_benchmark::dm_send::bench_dm_send text:setup_dm_send()`	177,556	177,971	-0.2%
`send_receive_benchmark::dm_recv::bench_dm_recv text:setup_dm_recv()`	191,784	191,870	-0.0%
`send_receive_benchmark::group_send::bench_group_send group_10:setup_group_send_10()`	888,990	888,986	+0.0%
`send_receive_benchmark::group_send::bench_group_send group_50:setup_group_send_50()`	980,393	980,188	+0.0%
`send_receive_benchmark::group_send::bench_group_send group_256:setup_group_send_256()`	1,465,403	1,465,398	+0.0%
`send_receive_benchmark::group_send_skdm::bench_group_send_skdm skdm_10:setup_group_skdm_10()`	2,721,818	2,744,114	-0.8%
`send_receive_benchmark::group_send_skdm::bench_group_send_skdm skdm_50:setup_group_skdm_50()`	10,056,630	10,141,275	-0.8%
`send_receive_benchmark::group_send_skdm::bench_group_send_skdm skdm_256:setup_group_skdm_256()`	47,874,720	48,311,928	-0.9%
`send_receive_benchmark::group_recv::bench_group_recv text:setup_group_recv()`	12,695,493	12,685,242	+0.1%
`binary_benchmark::marshal_group::bench_marshal_allocating`	95,585	95,585	+0.0%
`binary_benchmark::marshal_group::bench_marshal_auto_allocating`	95,618	95,618	+0.0%
`binary_benchmark::marshal_group::bench_marshal_exact_allocating`	113,974	113,974	+0.0%
`binary_benchmark::marshal_group::bench_marshal_reusing_buffer`	102,895	102,895	+0.0%
`binary_benchmark::marshal_group::bench_marshal_reusing_buffer_vec_writer`	95,685	95,685	+0.0%
`binary_benchmark::marshal_group::bench_marshal_long_string`	15,762	15,762	+0.0%
`binary_benchmark::marshal_group::bench_marshal_auto_long_string`	15,806	15,806	+0.0%
`binary_benchmark::marshal_group::bench_marshal_exact_long_string`	17,592	17,592	+0.0%
`binary_benchmark::marshal_group::bench_marshal_huge_bytes_allocating`	533,122	533,122	+0.0%
`binary_benchmark::marshal_group::bench_marshal_auto_huge_bytes_allocating`	532,688	532,688	+0.0%
`binary_benchmark::marshal_group::bench_marshal_exact_huge_bytes_allocating`	534,046	534,046	+0.0%
`binary_benchmark::marshal_group::bench_marshal_many_children_allocating`	13,413,012	13,413,012	+0.0%
`binary_benchmark::marshal_group::bench_marshal_auto_many_children_allocating`	13,357,245	13,357,245	+0.0%
`binary_benchmark::marshal_group::bench_marshal_exact_many_children_allocating`	26,652,528	26,652,528	+0.0%
`binary_benchmark::unmarshal_group::bench_unmarshal small:setup_small_marshaled()`	2,498	2,498	+0.0%
`binary_benchmark::unmarshal_group::bench_unmarshal large:setup_large_marshaled()`	38,500	38,500	+0.0%
`binary_benchmark::unpack_group::bench_unpack_uncompressed`	773	773	+0.0%
`binary_benchmark::unpack_group::bench_unpack_compressed`	556,090	556,090	+0.0%
`binary_benchmark::attr_parser_group::bench_attr_parser attr_lookup:setup_attr_marshaled()`	5,039	5,039	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip small:setup_small_marshaled()`	7,484	7,484	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip large:setup_large_marshaled()`	90,824	90,824	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip_auto small:setup_small_marshaled()`	7,511	7,511	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip_auto large:setup_large_marshaled()`	90,860	90,860	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip_exact small:setup_small_marshaled()`	8,838	8,838	+0.0%
`binary_benchmark::roundtrip_group::bench_roundtrip_exact large:setup_large_marshaled()`	104,670	104,670	+0.0%
`binary_benchmark::child_iteration_group::bench_get_children_by_tag`	475,970	475,970	+0.0%
`binary_benchmark::jid_optimization_group::bench_jid_to_owned_access jid_access:setup_jid_heavy_marshaled()`	13,493	13,493	+0.0%
`libsignal_benchmark::dm_group::bench_dm_session_establishment setup:setup_dm_users()`	17,382,958	17,187,816	+1.1%
`libsignal_benchmark::dm_group::bench_dm_encrypt_first_message first_msg:setup_dm_session()`	160,994	160,994	+0.0%
`libsignal_benchmark::dm_group::bench_dm_decrypt_first_message decrypt_prekey:setup_dm_with_first_message()`	5,511,244	5,511,244	+0.0%
`libsignal_benchmark::dm_group::bench_dm_encrypt_subsequent_message subsequent:setup_established_dm_session()`	161,731	161,731	+0.0%
`libsignal_benchmark::group_messaging_group::bench_group_create_distribution_message create:setup_group_sender()`	298,353	298,353	+0.0%
`libsignal_benchmark::group_messaging_group::bench_group_encrypt_message encrypt:setup_group_with_distribution()`	712,883	712,883	+0.0%
`libsignal_benchmark::group_messaging_group::bench_group_decrypt_message decrypt:setup_group_with_encrypted_message()`	12,586,974	12,455,803	+1.1%
`libsignal_benchmark::conversation_group::bench_full_dm_conversation full:setup_conversation_data()`	27,535,022	27,610,863	-0.3%
`libsignal_benchmark::signature_group::bench_signature_creation sign:setup_keypair_with_message()`	3,467,011	3,467,011	+0.0%
`libsignal_benchmark::signature_group::bench_signature_verification verify:setup_keypair_with_message()`	124,581,943	125,771,623	-0.9%
`libsignal_benchmark::signature_group::bench_key_generation keygen`	2,830,493	2,830,493	+0.0%
`libsignal_benchmark::session_optimization_group::bench_decrypt_with_previous_session previous_session:setup_with_archived_sessions()`	46,003	46,003	+0.0%
`libsignal_benchmark::session_optimization_group::bench_out_of_order_decryption out_of_order:setup_out_of_order_messages()`	5,105,272	5,105,272	+0.0%
`libsignal_benchmark::session_optimization_group::bench_promote_matching_session promote:setup_promote_matching_session()`	297,627	297,627	+0.0%
`libsignal_benchmark::session_optimization_group::bench_message_key_eviction eviction:setup_message_key_eviction()`	14,247,117	14,247,117	+0.0%

No significant changes detected.

coderabbitai Bot added the breaking-change label Apr 12, 2026

jlucaso1 merged commit 291ab58 into main Apr 12, 2026
8 checks passed

jlucaso1 deleted the perf/hot-path-allocation-reduction branch April 12, 2026 19:43

This was referenced Apr 13, 2026

perf!: reduce startup allocations by ~21% and peak heap by ~31% #525

Merged

fix: WA Web-compliant DM multi-device fanout with phash validation #524

Merged

perf: avoid unnecessary clone and pre-allocate Vecs in hot paths #545

Merged

coderabbitai Bot mentioned this pull request Apr 30, 2026

perf(send): parallelize group encrypt fan-out + adjacent wins #610

Merged

3 tasks

coderabbitai Bot mentioned this pull request May 14, 2026

fix: align inbound parsing with WA Web for receipts and messages #627

Merged

3 tasks

This was referenced May 29, 2026

perf(send): build encrypt-task Signal address from a borrow, not a Jid clone #662

Merged

fix(receipt): downgrade delivery ack to "sent" on lid feature-incapable error #708

Merged

This was referenced Jun 8, 2026

feat(receipt): expose the 'offline' attr on the Receipt event #780

Merged

perf(send): encode DM content once, splice into recipient + DSM plaintexts [PoC] #787

Merged

perf(send): splice reporting context onto plaintexts, drop per-send Message clone #788

Merged

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perf!: reduce hot-path allocations in receipt, send, and signal paths - #519

perf!: reduce hot-path allocations in receipt, send, and signal paths#519
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Summary

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Code Review: perf!: reduce hot-path allocations

1. Receipt construction — move semantics (src/receipt.rs)

2. Receipt.message_sender removal (wacore/src/types/events.rs)

3. encode_and_pad() (src/features/signal.rs, wacore/src/send.rs)

4. Redundant self-mapping removal (wacore/src/send.rs:405)

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jlucaso1 commented Apr 12, 2026 •

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claude Bot commented Apr 12, 2026 •

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Code Review: `perf!: reduce hot-path allocations`

1. Receipt construction — move semantics (`src/receipt.rs`)

2. `Receipt.message_sender` removal (`wacore/src/types/events.rs`)

3. `encode_and_pad()` (`src/features/signal.rs`, `wacore/src/send.rs`)

4. Redundant self-mapping removal (`wacore/src/send.rs:405`)