logs: skip temporary buffer between serialization and compression

[paulcacheux]

What does this PR do?

Currently when sending a log message to the backend, we first serialize the message to []byte then compress it. With this PR, the serialization is done directly to a io.Writer, alllowing to do the serialization and the compression at the same time, skipping the intermediary buffer completely.

Motivation

Describe how you validated your changes

Possible Drawbacks / Trade-offs

Additional Notes

[agent-platform-auto-pr]

Static quality checks ✅

Please find below the results from static quality gates

Info

Result	Quality gate	On disk size	On disk size limit	On wire size	On wire size limit
✅	static_quality_gate_agent_deb_amd64	844.57MiB	858.45MiB	203.59MiB	214.3MiB
✅	static_quality_gate_docker_agent_amd64	929.37MiB	942.69MiB	310.75MiB	321.56MiB

[agent-platform-auto-pr]

Uncompressed package size comparison

Comparison with ancestor ba9f4f1915e0337e5798541bbc533c74932241e0

Diff per package

package	diff	status	size	ancestor	threshold
datadog-agent-aarch64-rpm	0.02MB	⚠️	871.32MB	871.30MB	0.50MB
datadog-agent-arm64-deb	0.02MB	⚠️	861.60MB	861.58MB	0.50MB
datadog-agent-x86_64-rpm	0.01MB	⚠️	883.46MB	883.44MB	0.50MB
datadog-agent-x86_64-suse	0.01MB	⚠️	883.46MB	883.44MB	0.50MB
datadog-agent-amd64-deb	0.01MB	⚠️	873.72MB	873.70MB	0.50MB
datadog-dogstatsd-amd64-deb	0.01MB	⚠️	59.11MB	59.10MB	0.50MB
datadog-heroku-agent-amd64-deb	0.01MB	⚠️	445.91MB	445.91MB	0.50MB
datadog-dogstatsd-x86_64-rpm	0.01MB	⚠️	59.19MB	59.18MB	0.50MB
datadog-dogstatsd-x86_64-suse	0.01MB	⚠️	59.19MB	59.18MB	0.50MB
datadog-iot-agent-x86_64-rpm	0.01MB	⚠️	86.46MB	86.45MB	0.50MB
datadog-iot-agent-x86_64-suse	0.01MB	⚠️	86.45MB	86.45MB	0.50MB
datadog-iot-agent-amd64-deb	0.01MB	⚠️	86.39MB	86.38MB	0.50MB
datadog-iot-agent-aarch64-rpm	0.00MB	✅	82.72MB	82.72MB	0.50MB
datadog-dogstatsd-arm64-deb	0.00MB	✅	56.58MB	56.57MB	0.50MB
datadog-iot-agent-arm64-deb	0.00MB	✅	82.65MB	82.65MB	0.50MB

Decision

⚠️ Warning

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: fb843c27-87ab-4be3-b11f-81aa8001eb35

Baseline: ba9f4f1
Comparison: f061006
Diff

Optimization Goals: ✅ Improvement(s) detected

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
✅	quality_gate_logs	% cpu utilization	-5.67	[-8.60, -2.74]	1	Logs

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	tcp_syslog_to_blackhole	ingress throughput	+2.79	[+2.72, +2.86]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	+0.10	[+0.03, +0.17]	1	Logs bounds checks dashboard
➖	file_to_blackhole_100ms_latency	egress throughput	+0.01	[-0.64, +0.67]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	+0.01	[-0.83, +0.86]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	+0.00	[-0.87, +0.87]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.00	[-0.29, +0.28]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	-0.01	[-0.77, +0.74]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	-0.01	[-0.65, +0.62]	1	Logs
➖	file_tree	memory utilization	-0.02	[-0.08, +0.05]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	-0.09	[-0.87, +0.69]	1	Logs
➖	quality_gate_idle	memory utilization	-0.10	[-0.14, -0.06]	1	Logs bounds checks dashboard
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	-0.10	[-0.58, +0.37]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.27	[-1.14, +0.59]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.52	[-1.30, +0.25]	1	Logs
✅	quality_gate_logs	% cpu utilization	-5.67	[-8.60, -2.74]	1	Logs

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	links
✅	file_to_blackhole_0ms_latency	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http1	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http1	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http2	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http2	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency_linear_load	memory_usage	10/10
✅	file_to_blackhole_100ms_latency	lost_bytes	10/10
✅	file_to_blackhole_100ms_latency	memory_usage	10/10
✅	file_to_blackhole_300ms_latency	lost_bytes	10/10
✅	file_to_blackhole_300ms_latency	memory_usage	10/10
✅	file_to_blackhole_500ms_latency	lost_bytes	10/10
✅	file_to_blackhole_500ms_latency	memory_usage	10/10
✅	quality_gate_idle	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10
✅	quality_gate_logs	lost_bytes	10/10
✅	quality_gate_logs	memory_usage	10/10

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.

[agent-platform-auto-pr]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv aws.create-vm --pipeline-id=55329655 --os-family=ubuntu

Note: This applies to commit f061006