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fix(telemetry): refactor to shared_ptr and add deterministic shutdown() #326

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Merged
cataphract merged 3 commits into from
Jun 9, 2026
Merged

fix(telemetry): refactor to shared_ptr and add deterministic shutdown() #326

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cdf0fc0
fix(telemetry): refactor to shared_ptr and add deterministic shutdown()
cataphract Jun 4, 2026
cf43352
fix comment wording
cataphract Jun 8, 2026
31b8ae3
run clang-format
cataphract Jun 9, 2026
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19 changes: 19 additions & 0 deletions include/datadog/telemetry/telemetry.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,25 @@ void init(FinalizedConfiguration configuration,
tracing::HTTPClient::URL agent_url,
tracing::Clock clock = tracing::default_clock);

/// Deterministically shut down the telemetry module.
///
/// Cancels all scheduled tasks, sends the app-closing payload, and waits up
/// to 2 seconds for in-flight requests to complete (HTTPClient::drain()).
/// Then releases the HTTP client reference; if this is the last shared_ptr
/// to the client, the background Curl thread is joined synchronously and any
/// remaining in-flight requests are abandoned without firing their callbacks.
/// If other holders of the client remain, the Curl thread continues running
/// and requests may still complete and fire their callbacks after this call
/// returns (the callbacks guard against this with weak_from_this()). After
/// this call all telemetry send functions become no-ops. Safe to call even if
/// telemetry was never initialized, but must be called at most once after a
/// successful init.
///
/// Call this from the worker process exit path (e.g. before destroying the
/// tracer) so that telemetry's reference to the HTTP client is released
/// promptly, reducing the window before the Curl thread is quiesced.
void shutdown();

/// Sends configuration changes.
///
/// This function is responsible for sending reported configuration changes
Expand Down
114 changes: 67 additions & 47 deletions src/datadog/telemetry/telemetry.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ using NoopTelemetry = std::monostate;

/// `TelemetryProxy` holds either the real implementation or a no-op
/// implementation.
using TelemetryProxy = std::variant<NoopTelemetry, Telemetry>;
using TelemetryProxy = std::variant<NoopTelemetry, std::shared_ptr<Telemetry>>;

/// NOTE(@dmehala): Here to facilitate Meyer's singleton construction.
struct Ctor_param final {
Expand All @@ -37,9 +37,9 @@ struct Ctor_param final {

TelemetryProxy make_telemetry(const tracing::Optional<Ctor_param>& init) {
if (!init || !init->configuration.enabled) return NoopTelemetry{};
return Telemetry{init->configuration, init->tracer_signature, init->logger,
init->client, init->scheduler, init->agent_url,
init->clock};
return Telemetry::create(init->configuration, init->tracer_signature,
init->logger, init->client, init->scheduler,
init->agent_url, init->clock);
}

TelemetryProxy& instance(
Expand Down Expand Up @@ -69,20 +69,30 @@ void init(FinalizedConfiguration configuration,
event_scheduler, agent_url, clock});
}

void send_configuration_change() {
void shutdown() {
std::visit(
details::Overload{
[&](Telemetry& telemetry) { telemetry.send_configuration_change(); },
[](std::shared_ptr<Telemetry>& telemetry) { telemetry->shutdown(); },
[](NoopTelemetry) {},
},
instance());
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}

void send_configuration_change() {
std::visit(details::Overload{
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->send_configuration_change();
},
[](NoopTelemetry) {},
},
instance());
}

void capture_configuration_change(
const std::vector<tracing::ConfigMetadata>& new_configuration) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.capture_configuration_change(new_configuration);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->capture_configuration_change(new_configuration);
},
[](NoopTelemetry) {},
},
Expand All @@ -92,24 +102,28 @@ void capture_configuration_change(
namespace log {
void warning(std::string message) {
std::visit(details::Overload{
[&](Telemetry& telemetry) { telemetry.log_warning(message); },
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->log_warning(message);
},
[](NoopTelemetry) {},
},
instance());
}

void error(std::string message) {
std::visit(details::Overload{
[&](Telemetry& telemetry) { telemetry.log_error(message); },
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->log_error(message);
},
[](NoopTelemetry) {},
},
instance());
}

void error(std::string message, std::string stacktrace) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.log_error(message, stacktrace);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->log_error(message, stacktrace);
},
[](auto&&) {},
},
Expand All @@ -119,57 +133,60 @@ void error(std::string message, std::string stacktrace) {

namespace counter {
void increment(const Counter& counter) {
std::visit(
details::Overload{
[&](Telemetry& telemetry) { telemetry.increment_counter(counter); },
[](auto&&) {},
},
instance());
std::visit(details::Overload{
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->increment_counter(counter);
},
[](auto&&) {},
},
instance());
}

void increment(const Counter& counter, const std::vector<std::string>& tags) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.increment_counter(counter, tags);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->increment_counter(counter, tags);
},
[](auto&&) {},
},
instance());
}

void decrement(const Counter& counter) {
std::visit(
details::Overload{
[&](Telemetry& telemetry) { telemetry.decrement_counter(counter); },
[](auto&&) {},
},
instance());
std::visit(details::Overload{
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->decrement_counter(counter);
},
[](auto&&) {},
},
instance());
}

void decrement(const Counter& counter, const std::vector<std::string>& tags) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.decrement_counter(counter, tags);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->decrement_counter(counter, tags);
},
[](auto&&) {},
},
instance());
}

void set(const Counter& counter, uint64_t value) {
std::visit(
details::Overload{
[&](Telemetry& telemetry) { telemetry.set_counter(counter, value); },
[](auto&&) {},
},
instance());
std::visit(details::Overload{
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->set_counter(counter, value);
},
[](auto&&) {},
},
instance());
}

void set(const Counter& counter, const std::vector<std::string>& tags,
uint64_t value) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.set_counter(counter, tags, value);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->set_counter(counter, tags, value);
},
[](auto&&) {},
},
Expand All @@ -181,29 +198,32 @@ void set(const Counter& counter, const std::vector<std::string>& tags,
namespace rate {
void set(const Rate& rate, uint64_t value) {
std::visit(details::Overload{
[&](Telemetry& telemetry) { telemetry.set_rate(rate, value); },
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->set_rate(rate, value);
},
[](auto&&) {},
},
instance());
}

void set(const Rate& rate, const std::vector<std::string>& tags,
uint64_t value) {
std::visit(
details::Overload{
[&](Telemetry& telemetry) { telemetry.set_rate(rate, tags, value); },
[](auto&&) {},
},
instance());
std::visit(details::Overload{
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->set_rate(rate, tags, value);
},
[](auto&&) {},
},
instance());
}
} // namespace rate

namespace distribution {

void add(const Distribution& distribution, uint64_t value) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.add_datapoint(distribution, value);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->add_datapoint(distribution, value);
},
[](auto&&) {},
},
Expand All @@ -213,8 +233,8 @@ void add(const Distribution& distribution, uint64_t value) {
void add(const Distribution& distribution, const std::vector<std::string>& tags,
uint64_t value) {
std::visit(details::Overload{
[&](Telemetry& telemetry) {
telemetry.add_datapoint(distribution, tags, value);
[&](std::shared_ptr<Telemetry>& telemetry) {
telemetry->add_datapoint(distribution, tags, value);
},
[](auto&&) {},
},
Expand Down
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