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Trace size optimization: Remove unreferenced intern table entries in redacted traces #6912

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Trace size optimization: Remove unreferenced intern table entries in redacted traces #6912

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1af1147
Trace size optimization: Remove unreferenced intern table entries in …
edgararriagag Jul 28, 2026
ded2463
Merge branch 'main' into dev/edgararriagag/ea_interntable_optimization
edgararriagag Jul 29, 2026
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74 changes: 40 additions & 34 deletions src/trace_redaction/redact_sched_events.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -369,9 +369,12 @@ base::Status RedactSchedEvents::OnCompSched(
comp_sched.has_switch_next_comm_index(),
};

// The final intern table that will only contain referenced entries.
std::vector<std::string> dest_intern_table;

if (std::any_of(has_switch_fields.begin(), has_switch_fields.end(), IsTrue)) {
RETURN_IF_ERROR(
OnCompSchedSwitch(context, cpu, comp_sched, &intern_table, message));
RETURN_IF_ERROR(OnCompSchedSwitch(context, cpu, comp_sched, &intern_table,
&dest_intern_table, message));
}

std::array<bool, 6> has_waking_fields = {
Expand All @@ -381,14 +384,14 @@ base::Status RedactSchedEvents::OnCompSched(
};

if (std::any_of(has_waking_fields.begin(), has_waking_fields.end(), IsTrue)) {
RETURN_IF_ERROR(
OnCompactSchedWaking(context, comp_sched, &intern_table, message));
RETURN_IF_ERROR(OnCompactSchedWaking(context, comp_sched, &intern_table,
&dest_intern_table, message));
}

// IMPORTANT: The intern table can only be added after switch and waking
// because switch and/or waking can/will modify the intern table.
for (auto view : intern_table.values()) {
message->add_intern_table(view.data(), view.size());
for (const std::string& str : dest_intern_table) {
message->add_intern_table(str.c_str(), str.size());
}

return base::OkStatus();
Expand All @@ -398,7 +401,8 @@ base::Status RedactSchedEvents::OnCompSchedSwitch(
const Context& context,
int32_t cpu,
protos::pbzero::FtraceEventBundle::CompactSched::Decoder& comp_sched,
InternTable* intern_table,
InternTable* source_intern_table,
std::vector<std::string>* target_intern_table,
protos::pbzero::FtraceEventBundle::CompactSched* message) const {
PERFETTO_DCHECK(modifier_);
PERFETTO_DCHECK(message);
Expand Down Expand Up @@ -439,20 +443,23 @@ base::Status RedactSchedEvents::OnCompSchedSwitch(
auto pid = *it_pid;

auto comm_index = *it_comm;
auto comm = intern_table->Find(comm_index);
auto comm = source_intern_table->Find(comm_index);

scratch_str.assign(comm);

modifier_->Modify(context, ts, cpu, &pid, &scratch_str);

auto found = intern_table->Push(scratch_str.data(), scratch_str.size());

if (found < 0) {
return base::ErrStatus(
"RedactSchedEvents: failed to insert string into intern table.");
// Add the string to the intern table if it is not already there, otherwise,
// reuse it.
auto found = std::find(target_intern_table->begin(),
target_intern_table->end(), scratch_str);
if (found == target_intern_table->end()) {
target_intern_table->push_back(scratch_str);
packed_comm.Append(target_intern_table->size() - 1);
} else {
packed_comm.Append(std::distance(target_intern_table->begin(), found));
}

packed_comm.Append(found);
packed_pid.Append(pid);

++it_ts;
Expand Down Expand Up @@ -516,7 +523,8 @@ base::Status RedactSchedEvents::OnCompSchedSwitch(
base::Status RedactSchedEvents::OnCompactSchedWaking(
const Context& context,
protos::pbzero::FtraceEventBundle::CompactSched::Decoder& compact_sched,
InternTable* intern_table,
InternTable* source_intern_table,
std::vector<std::string>* target_intern_table,
protos::pbzero::FtraceEventBundle::CompactSched* compact_sched_message)
const {
protozero::PackedVarInt var_comm_index;
Expand Down Expand Up @@ -552,44 +560,42 @@ base::Status RedactSchedEvents::OnCompactSchedWaking(

std::string comm;

std::array<bool, 7> parse_errors = {!compact_sched.has_intern_table(),
false,
false,
false,
false,
false,
false};

std::array<bool, 6> parse_errors = {false, false, false, false, false, false};
// A note on readability, because the waking iterators are the primary focus,
// they won't have a "waking" prefix.
auto it_comm_index = compact_sched.waking_comm_index(&parse_errors.at(1));
auto it_common_flags = compact_sched.waking_common_flags(&parse_errors.at(2));
auto it_pid = compact_sched.waking_pid(&parse_errors.at(3));
auto it_prio = compact_sched.waking_prio(&parse_errors.at(4));
auto it_target_cpu = compact_sched.waking_target_cpu(&parse_errors.at(5));
auto it_timestamp = compact_sched.waking_timestamp(&parse_errors.at(6));
auto it_comm_index = compact_sched.waking_comm_index(&parse_errors.at(0));
auto it_common_flags = compact_sched.waking_common_flags(&parse_errors.at(1));
auto it_pid = compact_sched.waking_pid(&parse_errors.at(2));
auto it_prio = compact_sched.waking_prio(&parse_errors.at(3));
auto it_target_cpu = compact_sched.waking_target_cpu(&parse_errors.at(4));
auto it_timestamp = compact_sched.waking_timestamp(&parse_errors.at(5));

while (it_comm_index && it_common_flags && it_pid && it_prio &&
it_target_cpu && it_timestamp) {
ts_bucket += *it_timestamp; // add time to the bucket
ts_absolute += *it_timestamp;

if (waking_filter_->Includes(context, ts_absolute, *it_pid)) {
// Now that the waking event will be kept, it can be modified using the
// same rules as switch events.
auto pid = *it_pid;
comm.assign(intern_table->Find(*it_comm_index));
comm.assign(source_intern_table->Find(*it_comm_index));
modifier_->Modify(context, ts_absolute, *it_target_cpu, &pid, &comm);

auto comm_it = intern_table->Push(comm.data(), comm.size());
auto found = std::find(target_intern_table->begin(),
target_intern_table->end(), comm);
if (found == target_intern_table->end()) {
target_intern_table->push_back(comm);
var_comm_index.Append(target_intern_table->size() - 1);
} else {
var_comm_index.Append(
std::distance(target_intern_table->begin(), found));
}

var_comm_index.Append(comm_it);
var_common_flags.Append(*it_common_flags);
var_pid.Append(pid);
var_prio.Append(*it_prio);
var_target_cpu.Append(*it_target_cpu);
var_timestamp.Append(ts_bucket);

ts_bucket = 0; // drain the whole bucket.
}

Expand Down
6 changes: 4 additions & 2 deletions src/trace_redaction/redact_sched_events.h
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Original file line number Diff line number Diff line change
Expand Up @@ -102,13 +102,15 @@ class RedactSchedEvents : public TransformPrimitive {
const Context& context,
int32_t cpu,
protos::pbzero::FtraceEventBundle::CompactSched::Decoder& comp_sched,
InternTable* intern_table,
InternTable* source_intern_table,
std::vector<std::string>* target_intern_table,
protos::pbzero::FtraceEventBundle::CompactSched* message) const;

base::Status OnCompactSchedWaking(
const Context& context,
protos::pbzero::FtraceEventBundle::CompactSched::Decoder& compact_sched,
InternTable* intern_table,
InternTable* source_intern_table,
std::vector<std::string>* target_intern_table,
protos::pbzero::FtraceEventBundle::CompactSched* compact_sched_message)
const;

Expand Down
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