Custom Instrumentation

// Enable performance monitoring by setting a sample rate above 0
sentry_options_t *options = sentry_options_new();
sentry_options_set_traces_sample_rate(options, 0.2);
...
sentry_init(options);

// Transactions can be started by providing the name and the operation
sentry_transaction_context_t *tx_ctx = sentry_transaction_context_new(
    "transaction name",
    "transaction operation",
);
sentry_transaction_t *tx = sentry_transaction_start(tx_ctx, sentry_value_new_null());

// Transactions can have child spans (and those spans can have child spans as well)
sentry_span_t *span = sentry_transaction_start_child(
    tx,
    "child operation",
    "child description",
);

// ...
// (Perform the operation represented by the span/transaction)
// ...

sentry_span_finish(span); // Mark the span as finished
sentry_transaction_finish(tx); // Mark the transaction as finished and send it to Sentry

// Let's say this method is called in a background thread when a user clicks on the checkout button.
void perform_checkout() {
    // This will create a new Transaction for you
    sentry_transaction_context_t *tx_ctx = sentry_transaction_context_new(
        "checkout",
        "perform-checkout"
    );
    sentry_transaction_t *tx = sentry_transaction_start(tx_ctx, sentry_value_new_null());

    // Validate the cart
    sentry_span_t *validation_span = sentry_transaction_start_child(
        tx,
        "validation",
        "validating shopping cart",
    );

    validate_shopping_cart(); // Some long process, maybe a sync http request.

    sentry_span_finish(validation_span);

    // Process the order
    sentry_span_t *process_span = sentry_transaction_start_child(
        tx,
        "process",
        "processing shopping cart",
    )

    process_shopping_cart(); // Another time consuming process.

    sentry_span_finish(process_span);

    sentry_transaction_finish(tx);
}

/**
 * Constructs a new Transaction Context. The returned value needs to be passed
 * into `sentry_transaction_start` in order to be recorded and sent to sentry.
 *
 * [...]
 *
 * The returned value is not thread-safe. Users are expected to ensure that
 * appropriate locking mechanisms are implemented over the Transaction Context
 * if it needs to be mutated across threads. Methods operating on the
 * Transaction Context will mention what kind of expectations they carry if they
 * need to mutate or access the object in a thread-safe way.
 */

/**
 * Sets the `name` on a Transaction Context, which will be used in the
 * Transaction constructed off of the context.
 *
 * The Transaction Context should not be mutated by other functions while
 * setting a name on it.
 */

sentry_transaction_context_t *tx_ctx = sentry_transaction_context_new(
    "checkout",
    "perform-checkout",
);
sentry_transaction_t *tx = sentry_transaction_start(tx_ctx, sentry_value_new_null());

// Bind the transaction / span to the scope:
sentry_set_span(tx);

// Errors captured after the line above will be linked to the transaction
sentry_value_t exc = sentry_value_new_exception(
    "ParseIntError",
    "invalid digit found in string",
);

sentry_value_t event = sentry_value_new_event();
sentry_event_add_exception(event, exc);
sentry_capture_event(event);

sentry_transaction_finish(tx);

static void
copy_headers_to(const char *key, const char *value, void *userdata)
{
    sentry_value_t *headers
        = (sentry_value_t *)userdata;
    sentry_value_set_by_key(*headers, key, value);
}

int main(int argc, char **argv) {
  ...
	// Transaction to continue off of
	sentry_transaction_context_t *tx_ctx = sentry_transaction_context_new(
        "honk",
        NULL,
    );
    sentry_transaction_t *tx = sentry_transaction_start(tx_ctx, sentry_value_new_null());

	sentry_value_t *headers = sentry_value_new_object();
	sentry_transaction_iter_headers(tx, copy_headers_to, (void *)headers);
}

	sentry_transaction_context_t *tx_ctx = sentry_transaction_context_new(
        "honk",
        NULL,
    );
    sentry_transaction_context_update_from_header(
        tx_ctx,
        "sentry-trace",
        "atraceid-aspanid-issampled",
    );