C/C++ Application Instrumentation

Telegen automatically instruments C and C++ applications that use standard database client libraries — no recompilation, no SDK, no code changes.

Overview

C and C++ applications using standard database drivers produce the same wire protocols as applications written in other languages. Telegen’s generic TCP tracer already captures these wire protocols at the kernel level. The C/C++ instrumentation enhancement adds:

  1. Driver detection — Identifying C/C++ DB client libraries from process memory

  2. Language attribution — Setting process.language=cpp in spans and metrics

  3. DB system refinement — Resolving the correct db.system semantic convention

Supported Drivers

PostgreSQL

Library

Detection

Details

libpq

Symbol PQsendQuery / PQexec in process memory

Full PostgreSQL wire protocol v3 tracing

libpqxx (C++ wrapper)

Inherits libpq detection

Same as libpq

MySQL / MariaDB

Library

Detection

Details

libmysqlclient

Symbol mysql_query / mysql_real_query

Full MySQL client/server protocol tracing

mysqlcppconn (C++ wrapper)

Inherits libmysqlclient detection

Same as libmysqlclient

MSSQL / SQL Server

Library

Detection

Details

FreeTDS

TDS protocol detection + process name

TDS protocol tracing (v7.0+)

ODBC with FreeTDS driver

TDS protocol detection

Same as FreeTDS

Microsoft ODBC Driver

TDS protocol detection

Native Microsoft TDS driver

Oracle

Library

Detection

Details

libclntsh (OCI)

Symbol OCIStmtExecute

Oracle TNS/Net8 protocol tracing

How It Works

Wire Protocol Capture (Generic Tracer)

C/C++ applications using the above libraries produce standard wire protocols:

Application (C/C++)
    ↓
libpq / libmysqlclient / FreeTDS
    ↓
TCP socket write
    ↓
Linux kernel (eBPF kprobe)
    ↓
Generic tracer: protocol detection + frame parsing
    ↓
Span generation (PostgreSQLTraces, MySQLTraces, etc.)

No uprobes are needed — the generic kprobe-based TCP tracer captures the wire protocol regardless of the language.

Language Detection (Semconv Refinement)

Once a database span is generated, Telegen refines the db.system and process.language attributes:

  1. internal/semconv/dbsystem_refine.go checks the process executable for known C/C++ DB library symbols

  2. If matched, process.language=cpp is set on the span

  3. The db.system attribute is verified/refined (e.g., postgresql for libpq, mysql for libmysqlclient)

Sample Span (C++ with libpq)

span:
  name: "SELECT users"
  kind: CLIENT
  duration_ms: 2.3
  attributes:
    db.system: "postgresql"
    db.name: "myapp"
    db.statement: "SELECT id, name FROM users WHERE id = $1"
    db.operation: SELECT
    process.pid: 12345
    process.executable.name: "my_cpp_app"
    process.language: "cpp"
    process.runtime.description: "libpq (PostgreSQL C client)"
    net.peer.ip: "10.0.1.100"
    net.peer.port: 5432

Configuration

C/C++ instrumentation requires no special configuration. It is automatically enabled when:

  1. The generic tracer is active (agent.mode: agent or --mode agent)

  2. Database protocol tracing is not disabled

To verify C/C++ detection is working, check spans for the process.language=cpp attribute.

Comparison: C/C++ vs Go vs Java

Feature

C/C++

Go

Java

Wire protocol capture

Generic tracer (kprobe)

Generic tracer + uprobes

Generic tracer + uprobes

Language detection

Symbol scanning (dbsystem_refine.go)

Go pclntab parsing

JVM attach + perf maps

DB driver awareness

libpq, libmysqlclient, FreeTDS

database/sql, go-sql-driver, pgx

JDBC (generic)

Uprobe support

No (wire protocol only)

Yes (net/http, gRPC, database/sql, go-redis, mongo-driver, kafka-go)

Yes (TLS, JFR)

Symbol resolution

process.language=cpp

Full Go symbol resolution

Java JIT (with perf map)

Limitations

  • Prepared statements — C/C++ prepared statement names are captured from the wire protocol (PostgreSQL Parse/Bind messages, MySQL COM_STMT_PREPARE). This works the same as for any language.

  • Connection pooling — Connection pool libraries (e.g., libpq connection pools) are transparent — Telegen traces at the TCP level, so pooled connections are automatically covered.

  • Non-standard drivers — If a C/C++ application uses a non-standard or proprietary database protocol, Telegen cannot trace it unless the protocol is explicitly supported.

  • SSL/TLS — Encrypted database connections (SSL/TLS) cannot be traced at the wire level. Use sslmode=disable for development, or rely on application-level tracing.

Troubleshooting

C/C++ spans missing process.language=cpp

  1. Verify the process is using a supported library: ldd <binary> | grep -E 'libpq|libmysqlclient|libtds'

  2. Check that the generic tracer is capturing the wire protocol: telegen self-telemetry → check telegen_tracer_events_total for PostgreSQL/MySQL event types

  3. Ensure dbsystem_refine.go is not disabled in your build

Database queries not captured

  1. Verify the DB client library is not using Unix domain sockets — Telegen traces TCP connections only

  2. Check that the query is not over a local connection (localhost with shared memory)

  3. Verify the port is not excluded in the generic tracer port filter