diff options
| -rw-r--r-- | bbot/agent/agent.cxx | 133 |
1 files changed, 101 insertions, 32 deletions
diff --git a/bbot/agent/agent.cxx b/bbot/agent/agent.cxx index d58743b..1647fcf 100644 --- a/bbot/agent/agent.cxx +++ b/bbot/agent/agent.cxx @@ -21,6 +21,7 @@ #include <sys/socket.h> #include <map> +#include <atomic> #include <chrono> #include <random> #include <iomanip> // setw() @@ -51,6 +52,34 @@ using namespace bbot; using std::cout; using std::endl; +// According to the standard, atomic's use in the signal handler is only safe +// if it's lock-free. +// +#if !defined(ATOMIC_INT_LOCK_FREE) || ATOMIC_INT_LOCK_FREE != 2 +#error int is not lock-free on this architecture +#endif + +// While we can use memory_order_relaxed in a single-threaded program, let's +// use consume/release in case this process becomes multi-threaded in the +// future. +// +static std::atomic<unsigned int> sigurs1; + +using std::memory_order_consume; +using std::memory_order_release; + +extern "C" void +handle_signal (int sig) +{ + switch (sig) + { + case SIGHUP: exit (3); // Unimplemented feature. + case SIGTERM: exit (0); + case SIGUSR1: sigurs1.fetch_add (1, std::memory_order_release); break; + default: assert (false); + } +} + namespace bbot { agent_options ops; @@ -224,6 +253,8 @@ bootstrap_machine (const dir_path& md, m->wait (false); m->cleanup (); info << "resuming after machine suspension"; + + // Note: snapshot cleaned up by the caller of bootstrap_machine(). } catch (const failed&) {} @@ -274,7 +305,10 @@ bootstrap_machine (const dir_path& md, break; if (!check_machine ()) + { + // Note: snapshot cleaned up by the caller of bootstrap_machine(). return nullopt; + } } // This can mean two things: machine mis-configuration or what we @@ -317,7 +351,10 @@ bootstrap_machine (const dir_path& md, // The exit/upload is racy so we re-check. // if (!(file_not_empty (mf) || file_not_empty (mfo))) + { + // Note: snapshot cleaned up by the caller of bootstrap_machine(). return nullopt; + } } bool old (false); @@ -1211,7 +1248,12 @@ try { tracer trace ("perform_task", md.string ().c_str ()); - tl.unlock (); // @@ TMP (we have to arm the signal handler under lock). + // Arm the interrupt handler and release the global toolchain lock. + // + // Note that there can be no interrupt while we are holding the global lock. + // + sigurs1.store (0, std::memory_order_release); + tl.unlock (); result_manifest r { tm.name, @@ -1261,6 +1303,8 @@ try if (ops.fake_machine_specified ()) { + // Note: not handling interrupts here. + // Simply wait for the file to appear. // for (size_t i (0);; sleep (1)) @@ -1335,28 +1379,33 @@ try l3 ([&]{trace << "tftp server on port " << tftpd.port ();}); - // Start the machine. - // - unique_ptr<machine> m ( - start_machine (xp, - mm.machine, - mm.machine.mac, - ops.bridge (), - tftpd.port (), - tm.interactive.has_value ())); - - // Note: the machine handling logic is similar to bootstrap. + // Note: the machine handling logic is similar to bootstrap. Except here + // we have to cleanup the snapshot ourselves in case of suspension or + // unexpected exit. // { + // Start the machine. + // + unique_ptr<machine> m ( + start_machine (xp, + mm.machine, + mm.machine.mac, + ops.bridge (), + tftpd.port (), + tm.interactive.has_value ())); + auto mg ( make_exception_guard ( [&m, &xp] () { - info << "trying to force machine " << xp << " down"; - try {m->forcedown (false);} catch (const failed&) {} + if (m != nullptr) + { + info << "trying to force machine " << xp << " down"; + try {m->forcedown (false);} catch (const failed&) {} + } })); - auto soft_fail = [&ml, &xp, &m, &r] (const char* msg) + auto soft_fail = [&trace, &ml, &xp, &m, &r] (const char* msg) { { diag_record dr (error); @@ -1374,6 +1423,7 @@ try m->suspend (false); m->wait (false); m->cleanup (); + run_btrfs (trace, "subvolume", "delete", xp); info << "resuming after machine suspension"; } catch (const failed&) {} @@ -1389,9 +1439,7 @@ try if (!m->wait (t /* seconds */, false /* fail_hard */)) return true; } - catch (const failed&) - { - } + catch (const failed&) {} diag_record dr (warn); dr << "machine " << xp << " exited unexpectedly"; @@ -1400,6 +1448,22 @@ try return false; }; + auto check_interrupt = [&trace, &xp, &m] () + { + if (sigurs1.load (std::memory_order_consume) == 0) + return; + + // @@ l3 + l1 ([&]{trace << "machine " << xp << " interruped";}); + + try {m->forcedown (false);} catch (const failed&) {} + m->cleanup (); + m = nullptr; // Disable exceptions guard above. + run_btrfs (trace, "subvolume", "delete", xp); + + throw interrupt (); + }; + // The first request should be the task manifest download. Wait for up // to 2 minutes for that to arrive (again, that long to deal with // flaky Windows networking). In a sense we use it as an indication @@ -1411,15 +1475,21 @@ try ? ops.intactive_timeout () : ops.build_timeout ()); - // Wait periodically making sure the machine is still alive. + // Wait periodically making sure the machine is still alive and + // checking for interrupts. // for (to = startup_to; to != 0; ) { + check_interrupt (); + if (tftpd.serve (to, 2)) break; if (!check_machine ()) + { + run_btrfs (trace, "subvolume", "delete", xp); return r; + } } if (to == 0) @@ -1448,13 +1518,18 @@ try // for (to = build_to; to != 0; ) { + check_interrupt (); + if (tftpd.serve (to, 2)) continue; if (!check_machine ()) { if (!file_not_empty (rf)) + { + run_btrfs (trace, "subvolume", "delete", xp); return r; + } } if (file_not_empty (rf)) @@ -1490,6 +1565,10 @@ try // while uploading the archive and so the partially uploaded file // may exist. Thus, we check if the result status is not an error. // + // Note also that we will not bother with interrupting this process + // assuming it will be quick (relative to the amount of work that + // would be wasted). + // bool err (!rm || !rm->status); if (!err && file_exists (af)) { @@ -1579,7 +1658,7 @@ try } } - // Update package name/version if the returned value as "unknown". + // Update package name/version if the returned value is "unknown". // if (r.version == bpkg::version ("0")) { @@ -1596,17 +1675,6 @@ catch (const system_error& e) fail << "build error: " << e << endf; } -extern "C" void -handle_signal (int sig) -{ - switch (sig) - { - case SIGHUP: exit (3); // Unimplemented feature. - case SIGTERM: exit (0); - default: assert (false); - } -} - static const string agent_checksum ("2"); // Logic version. int @@ -1807,7 +1875,8 @@ try // Handle SIGHUP and SIGTERM. // if (signal (SIGHUP, &handle_signal) == SIG_ERR || - signal (SIGTERM, &handle_signal) == SIG_ERR) + signal (SIGTERM, &handle_signal) == SIG_ERR || + signal (SIGUSR1, &handle_signal) == SIG_ERR) fail << "unable to set signal handler: " << system_error (errno, std::generic_category ()); // Sanitize. |