Examples of using BCC C++ API

examples/CMakeLists.txt

 set(EXAMPLE_PROGRAMS hello_world.py)
 install(PROGRAMS ${EXAMPLE_PROGRAMS} DESTINATION share/bcc/examples)
 
+add_subdirectory(cpp)
+add_subdirectory(lua)
 add_subdirectory(networking)
 add_subdirectory(tracing)
-add_subdirectory(lua)
\ No newline at end of file

examples/cpp/CMakeLists.txt

+# Copyright (c) Facebook, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+include_directories(${CMAKE_SOURCE_DIR}/src/cc)
+
+add_executable(HelloWorld HelloWorld.cc)
+target_link_libraries(HelloWorld bcc-static)
+install (TARGETS HelloWorld DESTINATION share/bcc/examples/cpp)
+
+add_executable(CPUDistribution CPUDistribution.cc)
+target_link_libraries(CPUDistribution bcc-static)
+install (TARGETS CPUDistribution DESTINATION share/bcc/examples/cpp)
+
+add_executable(RecordMySQLQuery RecordMySQLQuery.cc)
+target_link_libraries(RecordMySQLQuery bcc-static)
+install (TARGETS RecordMySQLQuery DESTINATION share/bcc/examples/cpp)
+
+add_executable(TCPSendStack TCPSendStack.cc)
+target_link_libraries(TCPSendStack bcc-static)
+install (TARGETS TCPSendStack DESTINATION share/bcc/examples/cpp)
+
+add_executable(RandomRead RandomRead.cc)
+target_link_libraries(RandomRead bcc-static)
+install (TARGETS RandomRead DESTINATION share/bcc/examples/cpp)

examples/cpp/CPUDistribution.cc

+/*
+ * CPUDistribution Show load distribution across CPU cores during a period of
+ *                 time. For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC and kprobes.
+ *
+ * USAGE: CPUDistribution [duration]
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+BPF_HASH(pid_to_cpu, pid_t, int);
+BPF_HASH(pid_to_ts, pid_t, uint64_t);
+BPF_HASH(cpu_time, int, uint64_t);
+
+int task_switch_event(struct pt_regs *ctx, struct task_struct *prev) {
+  pid_t prev_pid = prev->pid;
+  int* prev_cpu = pid_to_cpu.lookup(&prev_pid);
+  uint64_t* prev_ts = pid_to_ts.lookup(&prev_pid);
+
+  pid_t cur_pid = bpf_get_current_pid_tgid();
+  int cur_cpu = bpf_get_smp_processor_id();
+  uint64_t cur_ts = bpf_ktime_get_ns();
+
+  uint64_t this_cpu_time = 0;
+  if (prev_ts) {
+    pid_to_ts.delete(&prev_pid);
+    this_cpu_time = (cur_ts - *prev_ts);
+  }
+  if (prev_cpu) {
+    pid_to_cpu.delete(&prev_pid);
+    if (this_cpu_time > 0) {
+      int cpu_key = *prev_cpu;
+      uint64_t* history_time = cpu_time.lookup(&cpu_key);
+      if (history_time)
+        this_cpu_time += *history_time;
+      cpu_time.update(&cpu_key, &this_cpu_time);
+    }
+  }
+
+  pid_to_cpu.update(&cur_pid, &cur_cpu);
+  pid_to_ts.update(&cur_pid, &cur_ts);
+
+  return 0;
+}
+)";
+
+int main(int argc, char** argv) {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf.attach_kprobe("finish_task_switch", "task_switch_event");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc == 2) {
+    probe_time = atoi(argv[1]);
+  }
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table = bpf.get_hash_table<int, uint64_t>("cpu_time");
+  auto num_cores = sysconf(_SC_NPROCESSORS_ONLN);
+  for (int i = 0; i < num_cores; i++) {
+    std::cout << "CPU " << std::setw(2) << i << " worked for ";
+    std::cout << (table[i] / 1000000.0) << " ms." << std::endl;
+  }
+
+  auto detach_res = bpf.detach_kprobe("finish_task_switch");
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}

examples/cpp/HelloWorld.cc

+/*
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <fstream>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+int on_sys_clone(void *ctx) {
+  bpf_trace_printk("Hello, World! Here I did a sys_clone call!\n");
+  return 0;
+}
+)";
+
+int main() {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  std::ifstream pipe("/sys/kernel/debug/tracing/trace_pipe");
+  std::string line;
+
+  auto attach_res = bpf.attach_kprobe("sys_clone", "on_sys_clone");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  while (true) {
+    if (std::getline(pipe, line)) {
+      std::cout << line << std::endl;
+      // Detach the probe if we got at least one line.
+      auto detach_res = bpf.detach_kprobe("sys_clone");
+      if (std::get<0>(detach_res) != 0) {
+        std::cerr << std::get<1>(detach_res) << std::endl;
+        return 1;
+      }
+      break;
+    } else {
+      std::cout << "Waiting for a sys_clone event" << std::endl;
+      sleep(1);
+    }
+  }
+
+  return 0;
+}

examples/cpp/RandomRead.cc

+/*
+ * RandomRead Monitor random number read events.
+ *            For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC Tracepoint and perf buffer.
+ *
+ * USAGE: RandomRead
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <signal.h>
+#include <iostream>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+struct urandom_read_args {
+  // See /sys/kernel/debug/tracing/events/random/urandom_read/format
+  uint64_t common__unused;
+  int got_bits;
+  int pool_left;
+  int input_left;
+};
+
+struct event_t {
+  int pid;
+  char comm[16];
+  int got_bits;
+};
+
+BPF_PERF_OUTPUT(events);
+
+int on_urandom_read(struct urandom_read_args* attr) {
+  struct event_t event = {};
+  event.pid = bpf_get_current_pid_tgid();
+  bpf_get_current_comm(&event.comm, sizeof(event.comm));
+  event.got_bits = attr->got_bits;
+
+  events.perf_submit(attr, &event, sizeof(event));
+  return 0;
+}
+)";
+
+// Define the same struct to use in user space.
+struct event_t {
+  int pid;
+  char comm[16];
+  int got_bits;
+};
+
+void handle_output(void* cb_cookie, void* data, int data_size) {
+  auto event = static_cast<event_t*>(data);
+  std::cout << "PID: " << event->pid << " (" << event->comm << ") "
+            << "Read " << event->got_bits << " bits" << std::endl;
+}
+
+ebpf::BPF* bpf;
+
+void signal_handler(int s) {
+  std::cerr << "Terminating..." << std::endl;
+  delete bpf;
+  exit(0);
+}
+
+int main(int argc, char** argv) {
+  bpf = new ebpf::BPF();
+  auto init_res = bpf->init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf->attach_tracepoint("random:urandom_read", "on_urandom_read");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  auto open_res = bpf->open_perf_buffer("events", &handle_output);
+  if (std::get<0>(open_res) != 0) {
+    std::cerr << std::get<1>(open_res) << std::endl;
+    return 1;
+  }
+
+  signal(SIGINT, signal_handler);
+  std::cout << "Started tracing, hit Ctrl-C to terminate." << std::endl;
+  while (true)
+    bpf->poll_perf_buffer("events");
+
+  return 0;
+}

examples/cpp/RecordMySQLQuery.cc

+/*
+ * RecordMySQLQuery Record MySQL queries by probing the alloc_query() function
+ *                  in mysqld. For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC and uprobes.
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <algorithm>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/ptrace.h>
+
+struct query_probe_t {
+  uint64_t ts;
+  pid_t pid;
+  char query[100];
+};
+
+BPF_HASH(queries, struct query_probe_t, int);
+
+int probe_mysql_query(struct pt_regs *ctx, void* thd, char* query, size_t len) {
+  if (query) {
+    struct query_probe_t key = {};
+
+    key.ts = bpf_ktime_get_ns();
+    key.pid = bpf_get_current_pid_tgid();
+
+    bpf_probe_read(&key.query, sizeof(key.query), query);
+
+    int one = 1;
+    queries.update(&key, &one);
+  }
+  return 0;
+}
+)";
+const std::string ALLOC_QUERY_FUNC = "_Z11alloc_queryP3THDPKcj";
+
+// Define the same struct to use in user space.
+struct query_probe_t {
+  uint64_t ts;
+  pid_t pid;
+  char query[100];
+};
+
+int main(int argc, char** argv) {
+  if (argc < 2) {
+    std::cout << "USAGE: RecordMySQLQuery PATH_TO_MYSQLD [duration]"
+              << std::endl;
+    exit(1);
+  }
+
+  std::string mysql_path(argv[1]);
+  std::cout << "Using mysqld path: " << mysql_path << std::endl;
+
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf.attach_uprobe(mysql_path, ALLOC_QUERY_FUNC, "probe_mysql_query");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc >= 3)
+    probe_time = atoi(argv[2]);
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table_handle = bpf.get_hash_table<query_probe_t, int>("queries");
+  auto table = table_handle.get_table_offline();
+  std::sort(table.begin(), table.end(), [](std::pair<query_probe_t, int> a,
+                                           std::pair<query_probe_t, int> b) {
+    return a.first.ts < b.first.ts;
+  });
+  std::cout << table.size() << " queries recorded:" << std::endl;
+  for (auto it : table) {
+    std::cout << "Time: " << it.first.ts << " PID: " << it.first.pid
+              << " Query: " << it.first.query << std::endl;
+  }
+
+  auto detach_res = bpf.detach_uprobe(mysql_path, ALLOC_QUERY_FUNC);
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}

examples/cpp/TCPSendStack.cc

+/*
+ * TCPSendStack Summarize tcp_sendmsg() calling stack traces.
+ *              For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC in-kernel stack trace dedup.
+ *
+ * USAGE: TCPSendStack [duration]
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <algorithm>
+#include <iostream>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+struct stack_key_t {
+  int pid;
+  char name[16];
+  int user_stack;
+  int kernel_stack;
+};
+
+BPF_STACK_TRACE(stack_traces, 10240)
+BPF_HASH(counts, struct stack_key_t, uint64_t);
+
+int on_tcp_send(struct pt_regs *ctx) {
+  struct stack_key_t key = {};
+  key.pid = bpf_get_current_pid_tgid();
+  bpf_get_current_comm(&key.name, sizeof(key.name));
+  key.kernel_stack = stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID);
+  key.user_stack = stack_traces.get_stackid(
+    ctx, BPF_F_REUSE_STACKID | BPF_F_USER_STACK
+  );
+
+  u64 zero = 0, *val;
+  val = counts.lookup_or_init(&key, &zero);
+  (*val)++;
+
+  return 0;
+}
+)";
+
+// Define the same struct to use in user space.
+struct stack_key_t {
+  int pid;
+  char name[16];
+  int user_stack;
+  int kernel_stack;
+};
+
+int main(int argc, char** argv) {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res = bpf.attach_kprobe("tcp_sendmsg", "on_tcp_send");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc == 2) {
+    probe_time = atoi(argv[1]);
+  }
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table =
+      bpf.get_hash_table<stack_key_t, uint64_t>("counts").get_table_offline();
+  std::sort(table.begin(), table.end(), [](std::pair<stack_key_t, uint64_t> a,
+                                           std::pair<stack_key_t, uint64_t> b) {
+    return a.second < b.second;
+  });
+  auto stacks = bpf.get_stack_table("stack_traces");
+
+  for (auto it : table) {
+    std::cout << "PID: " << it.first.pid << " (" << it.first.name << ") "
+              << "made " << it.second
+              << " TCP sends on following stack: " << std::endl;
+    std::cout << "  Kernel Stack:" << std::endl;
+    if (it.first.kernel_stack >= 0) {
+      auto syms = stacks.get_stack_symbol(it.first.kernel_stack, -1);
+      for (auto sym : syms)
+        std::cout << "    " << sym << std::endl;
+    } else
+      std::cout << "    " << it.first.kernel_stack << std::endl;
+    std::cout << "  User Stack:" << std::endl;
+    if (it.first.user_stack >= 0) {
+      auto syms = stacks.get_stack_symbol(it.first.user_stack, it.first.pid);
+      for (auto sym : syms)
+        std::cout << "    " << sym << std::endl;
+    } else
+      std::cout << "    " << it.first.user_stack << std::endl;
+  }
+
+  auto detach_res = bpf.detach_kprobe("tcp_sendmsg");
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}