// file : libbuild2/rule-adhoc-cxx.cxx -*- C++ -*- // license : MIT; see accompanying LICENSE file #include <libbuild2/rule-adhoc-cxx.hxx> #include <libbutl/filesystem.mxx> // file_time() #include <libbuild2/file.hxx> #include <libbuild2/scope.hxx> #include <libbuild2/target.hxx> #include <libbuild2/context.hxx> #include <libbuild2/algorithm.hxx> #include <libbuild2/diagnostics.hxx> using namespace butl; namespace build2 { // cxx_rule_v1 // bool cxx_rule_v1:: match (action, target&, const string&) const { return true; } // adhoc_cxx_rule // adhoc_cxx_rule:: adhoc_cxx_rule (const location& l, size_t b, uint64_t v, optional<string> s) : adhoc_rule ("<ad hoc c++ recipe>", l, b), version (v), separator (move (s)), impl (nullptr) { if (v != 1) fail (l) << "unsupported c++ recipe version " << v; } bool adhoc_cxx_rule:: recipe_text (context&, const target&, string&& t, attributes&) { code = move (t); return true; } adhoc_cxx_rule:: ~adhoc_cxx_rule () { delete impl.load (memory_order_relaxed); // Serial execution. } void adhoc_cxx_rule:: dump_text (ostream& os, string& ind) const { // @@ TODO: indentation is multi-line recipes is off (would need to insert // indentation after every newline). // os << ind << string (braces, '{') << " c++ " << version << endl << ind << code << ind << string (braces, '}'); } #if defined(BUILD2_BOOTSTRAP) || defined(LIBBUILD2_STATIC_BUILD) bool adhoc_cxx_rule:: match (action, target&, const string&) const { // Note that we wait until match() (instead of, say, failing in the // parser) to allow the presence of ad hoc C++ recipes for other // operations. // fail (loc) << "ad hoc c++ recipe" << #ifdef BUILD2_BOOTSTRAP info << "running bootstrap build system" << endf; #else info << "running statically-linked build system" << endf; #endif } #else // From module.cxx. // void create_module_context (context&, const location&); const target& update_in_module_context (context&, const scope&, names tgt, const location&, const path& bf); pair<void*, void*> load_module_library (const path& lib, const string& sym, string& err); bool adhoc_cxx_rule:: match (action a, target& t, const string& hint) const { tracer trace ("adhoc_cxx_rule::match"); context& ctx (t.ctx); const scope& rs (t.root_scope ()); // The plan is to reduce this to the build system module case as much as // possible. Specifically, we switch to the load phase, create a module- // like library with the recipe text as a rule implementation, then build // and load it. // // Since the recipe can be shared among multiple targets, several threads // can all be trying to do this in parallel. // // We use the relaxed memory order here because any change must go through // the serial load phase. In other words, all we need here is atomicity // with ordering/visibility provided by the phase mutex. // cxx_rule* impl (this->impl.load (memory_order_relaxed)); while (impl == nullptr) // Breakout loop. { // Switch the phase to (serial) load and re-check. // phase_switch ps (ctx, run_phase::load); if ((impl = this->impl.load (memory_order_relaxed)) != nullptr) break; using create_function = cxx_rule_v1* (const location&, target_state); using load_function = create_function* (); // The only way to guarantee that the name of our module matches its // implementation is to based the name on the implementation hash (plus // the language, in case we support other compiled implementations in // the future). // // Unfortunately, this means we will be creating a new project (and // leaving behind the old one as garbage) for every change to the // recipe. On the other hand, if the recipe is moved around unchanged, // we will reuse the same project. In fact, two different recipes (e.g., // in different buildfiles) with the same text will share the project. // // The fact that we don't incorporate the recipe location into the hash // but include it in the source (in the form of the #line directive; see // below) has its own problems. If we do nothing extra here, then if a // "moved" but otherwise unchanged recipe is updated (for example, // because of changes in the build system core), then we may end up with // bogus location in the diagnostics. // // The straightforward solution would be to just update the location in // the source code if it has changed. This, however, will lead to // unnecessary and probably surprising recompilations since any line // count change before the recipe will trigger this update. One key // observation here is that we need accurate location information only // if we are going to recompile the recipe but the change to location // itself does not render the recipe out of date. So what we going to do // is factor the location information into its own small header and then // keep it up-to-date without changing its modification time. // // This works well if the project is not shared by multiple recipes. // However, if we have recipes in several buildfiles with identical // text, then the location information may end up yo-yo'ing depending on // which recipe got here first. // // There doesn't seem to be much we can do about it without incurring // other drawbacks/overheads. So the answer is for the user to use an ad // hoc rule with the common implementation instead of a bunch of // duplicate recipes. // string id; { sha256 cs; cs.append ("c++"); cs.append (separator ? *separator : ""); cs.append (code); id = cs.abbreviated_string (12); } dir_path pd (rs.out_path () / rs.root_extra->build_build_dir / recipes_build_dir /= id); path bf (pd / std_buildfile_file); string sym ("load_" + id); // Check whether the file exists and its last line matches the specified // signature. // // Note: we use the last instead of the first line for extra protection // against incomplete writes. // auto check_sig = [] (const path& f, const string& s) -> bool { try { if (!file_exists (f)) return false; ifdstream ifs (f); string l; while (ifs.peek () != ifdstream::traits_type::eof ()) getline (ifs, l); return l == s; } catch (const io_error& e) { fail << "unable to read " << f << ": " << e << endf; } catch (const system_error& e) { fail << "unable to access " << f << ": " << e << endf; } }; // Calculate (and cache) the global/local fragments split. // struct fragments { size_t global_p; // Start position. size_t global_n; // Length (0 if no global fragment). location global_l; // Position. size_t local_p; size_t local_n; location local_l; }; auto split = [this, f = optional<fragments> ()] () mutable -> const fragments& { if (f) return *f; // Note that the code starts from the next line thus +1. // location gl (loc.file, loc.line + 1, 1); if (!separator) { f = fragments {0, 0, location (), 0, code.size (), gl}; return *f; } // Iterate over lines (keeping track of the current line) looking // for the separator. // uint64_t l (gl.line); for (size_t b (0), e (b), n (code.size ()); b < n; b = e + 1, l++) { if ((e = code.find ('\n', b)) == string::npos) e = n; // Trim the line. // size_t tb (b), te (e); auto ws = [] (char c) {return c == ' ' || c == '\t' || c == '\r';}; for (; tb != te && ws (code[tb ]); ++tb) ; for (; te != tb && ws (code[te - 1]); --te) ; // text << "'" << string (code, tb, te - tb) << "'"; if (code.compare (tb, te - tb, *separator) == 0) { // End the global fragment at the previous newline and start the // local fragment at the beginning of the next line. // location ll (loc.file, l + 1, 1); if (++e >= n) fail (ll) << "empty c++ recipe local fragment"; f = fragments {0, b, gl, e, n - e, ll}; return *f; } } fail (loc) << "c++ recipe fragment separator '" << *separator << "' not found" << endf; }; bool nested (ctx.module_context == &ctx); // Create the build context if necessary. // if (ctx.module_context == nullptr) { if (!ctx.module_context_storage) fail (loc) << "unable to update ad hoc recipe for target " << t << info << "building of ad hoc recipes is disabled"; create_module_context (ctx, loc); } // "Switch" to the module context. // context& ctx (*t.ctx.module_context); const uint16_t verbosity (3); // Project creation command verbosity. // Project and location signatures. // // Specifically, we update the project version when changing anything // which would make the already existing projects unusable. // const string& lf (!loc.file.path.empty () ? loc.file.path.string () : loc.file.name ? *loc.file.name : string ()); const string psig ("# c++ " + to_string (version)); const string lsig ("// " + lf + ':' + to_string (loc.line)); // Check whether we need to (re)create the project. // optional<bool> altn (false); // Standard naming scheme. bool create (!is_src_root (pd, altn)); if (!create && (create = !check_sig (bf, psig))) rmdir_r (ctx, pd, false, verbosity); // Never dry-run. path of; ofdstream ofs; if (create) try { const fragments& frag (split ()); // Write ad hoc config.build that loads the ~build2 configuration. // This way the configuration will be always in sync with ~build2 // and we can update the recipe manually (e.g., for debugging). // create_project ( pd, dir_path (), /* amalgamation */ {}, /* boot_modules */ "cxx.std = latest", /* root_pre */ {"cxx."}, /* root_modules */ "", /* root_post */ string ("config"), /* config_module */ string ("config.config.load = ~build2"), /* config_file */ false, /* buildfile */ "build2 core", /* who */ verbosity); /* verbosity */ // Write the rule source file. // of = path (pd / "rule.cxx"); if (verb >= verbosity) text << (verb >= 2 ? "cat >" : "save ") << of; ofs.open (of); ofs << "#include \"location.hxx\"" << '\n' << '\n'; // Include every header that can plausibly be needed by a rule. // // @@ TMP: any new headers to add? [Keep this note for review.] // ofs << "#include <libbuild2/types.hxx>" << '\n' << "#include <libbuild2/forward.hxx>" << '\n' << "#include <libbuild2/utility.hxx>" << '\n' << '\n' << "#include <libbuild2/file.hxx>" << '\n' << "#include <libbuild2/rule.hxx>" << '\n' << "#include <libbuild2/depdb.hxx>" << '\n' << "#include <libbuild2/scope.hxx>" << '\n' << "#include <libbuild2/target.hxx>" << '\n' << "#include <libbuild2/context.hxx>" << '\n' << "#include <libbuild2/variable.hxx>" << '\n' << "#include <libbuild2/algorithm.hxx>" << '\n' << "#include <libbuild2/filesystem.hxx>" << '\n' << "#include <libbuild2/diagnostics.hxx>" << '\n' << "#include <libbuild2/rule-adhoc-cxx.hxx>" << '\n' << '\n'; // Write the global fragment, if any. Note that it always includes the // trailing newline. // if (frag.global_n != 0) { // Use the #line directive to point diagnostics to the code in the // buildfile. Note that there is no easy way to restore things to // point back to the source file (other than another #line with a // line and a file). Let's not bother for now. // ofs << "#line RECIPE_GLOBAL_LINE RECIPE_FILE" << '\n'; ofs.write (code.c_str () + frag.global_p, frag.global_n); ofs << '\n'; } // Normally the recipe code will have one level of indentation so // let's not indent the namespace level to match. // ofs << "namespace build2" << '\n' << "{" << '\n' << '\n'; // If we want the user to be able to supply a custom constuctor, then // we have to give the class a predictable name (i.e., we cannot use // id as part of its name) and put it into an unnamed namespace. One // clever idea is to call the class `constructor` but the name could // also be used for a custom destructor (still could work) or for name // qualification (would definitely look bizarre). // // In this light the most natural name is probable `rule`. The issue // is we already have this name in the build2 namespace (and its our // indirect base). In fact, any name that we choose could in the // future conflict with something in that namespace so maybe it makes // sense to bite the bullet and pick a name that is least likely to be // used by the user directly (can always use cxx_rule instead). // ofs << "namespace" << '\n' << "{" << '\n' << "class rule: public cxx_rule_v1" << '\n' << "{" << '\n' << "public:" << '\n' << '\n'; // Inherit base constructor. This way the user may provide their own // but don't have to. // ofs << " using cxx_rule_v1::cxx_rule_v1;" << '\n' << '\n'; // An extern "C" function cannot throw which can happen in case of a // user-defined constructor. So we need an extra level of indirection. // We incorporate id to make sure it doesn't conflict with anything // user-defined. // ofs << " static cxx_rule_v1*" << '\n' << " create_" << id << " (const location& l, target_state s)" << '\n' << " {" << '\n' << " return new rule (l, s);" << '\n' << " }" << '\n' << '\n'; // Use the #line directive to point diagnostics to the code in the // buildfile similar to the global fragment above. // ofs << "#line RECIPE_LOCAL_LINE RECIPE_FILE" << '\n'; // Note that the local fragment always includes the trailing newline. // ofs.write (code.c_str () + frag.local_p, frag.local_n); ofs << "};" << '\n' << '\n'; // Add an alias that we can use unambiguously in the load function. // ofs << "using rule_" << id << " = rule;" << '\n' << "}" << '\n' << '\n'; // Entry point. // ofs << "extern \"C\"" << '\n' << "#ifdef _WIN32" << '\n' << "__declspec(dllexport)" << '\n' << "#endif" << '\n' << "cxx_rule_v1* (*" << sym << " ()) (const location&, target_state)" << '\n' << "{" << '\n' << " return &rule_" << id << "::create_" << id << ";" << '\n' << "}" << '\n' << '\n'; ofs << "}" << '\n'; ofs.close (); // Write buildfile. // of = bf; if (verb >= verbosity) text << (verb >= 2 ? "cat >" : "save ") << of; ofs.open (of); ofs << "import imp_libs += build2%lib{build2}" << '\n' << "libs{" << id << "}: cxx{rule} hxx{location} $imp_libs" << '\n' << '\n' << "if ($cxx.target.system == 'win32-msvc')" << '\n' << " cxx.poptions += -D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_WARNINGS" << '\n' << '\n' << "if ($cxx.class == 'msvc')" << '\n' << " cxx.coptions += /wd4251 /wd4275 /wd4800" << '\n' << '\n' << psig << '\n'; ofs.close (); } catch (const io_error& e) { fail << "unable to write to " << of << ": " << e; } // Update the library target in the module context. // const target* l (nullptr); do // Breakout loop. { // Load the project in the module context. // // Note that it's possible it has already been loaded (see above about // the id calculation). // scope& rs (load_project (ctx, pd, pd, false /* forwarded */)); auto find_target = [&ctx, &rs, &pd, &id] () { const target_type* tt (rs.find_target_type ("libs")); assert (tt != nullptr); const target* t ( ctx.targets.find (*tt, pd, dir_path () /* out */, id)); assert (t != nullptr); return t; }; // If the project has already been loaded then, as an optimization, // check if the target has already been updated (this will make a // difference we if we have identical recipes in several buildfiles, // especially to the location update that comes next). // if (!source_once (rs, rs, bf)) { l = find_target (); if (l->executed_state (perform_update_id) != target_state::unknown) break; } // Create/update the recipe location header. // // For update, preserve the file timestamp in order not to render the // recipe out of date. // of = path (pd / "location.hxx"); if (!check_sig (of, lsig)) try { const fragments& frag (split ()); entry_time et (file_time (of)); if (verb >= verbosity) text << (verb >= 2 ? "cat >" : "save ") << of; ofs.open (of); // Recipe file and line for the #line directive above. We also need // to escape backslashes (Windows paths). // ofs << "#define RECIPE_FILE \"" << sanitize_strlit (lf) << '"'<< '\n'; if (frag.global_n != 0) ofs << "#define RECIPE_GLOBAL_LINE " << frag.global_l.line << '\n'; ofs << "#define RECIPE_LOCAL_LINE " << frag.local_l.line << '\n' << '\n' << lsig << '\n'; ofs.close (); if (et.modification != timestamp_nonexistent) file_time (of, et); } catch (const io_error& e) { fail << "unable to write to " << of << ": " << e; } catch (const system_error& e) { fail << "unable to get/set timestamp for " << of << ": " << e; } if (nested) { // This means there is a perform update action already in progress // in this context. So we are going to switch the phase and // perform direct match and update (similar how we do this for // generated headers). // // Note that since neither match nor execute are serial phases, it // means other targets in this context can be matched and executed // in paralellel with us. // if (l == nullptr) l = find_target (); phase_switch mp (ctx, run_phase::match); if (build2::match (perform_update_id, *l) != target_state::unchanged) { phase_switch ep (ctx, run_phase::execute); execute (a, *l); } } else { // Cutoff the existing diagnostics stack and push our own entry. // diag_frame::stack_guard diag_cutoff (nullptr); auto df = make_diag_frame ( [this, &t] (const diag_record& dr) { dr << info (loc) << "while updating ad hoc recipe for target " << t; }); l = &update_in_module_context ( ctx, rs, names {name (pd, "libs", id)}, loc, bf); } } while (false); // Load the library. // const path& lib (l->as<file> ().path ()); // Note again that it's possible the library has already been loaded // (see above about the id calculation). // string err; pair<void*, void*> hs (load_module_library (lib, sym, err)); // These normally shouldn't happen unless something is seriously broken. // if (hs.first == nullptr) fail (loc) << "unable to load recipe library " << lib << ": " << err; if (hs.second == nullptr) fail (loc) << "unable to lookup " << sym << " in recipe library " << lib << ": " << err; { auto df = make_diag_frame ( [this](const diag_record& dr) { if (verb != 0) dr << info (loc) << "while initializing ad hoc recipe"; }); load_function* lf (function_cast<load_function*> (hs.second)); create_function* cf (lf ()); impl = cf (loc, l->executed_state (perform_update_id)); this->impl.store (impl, memory_order_relaxed); // Still in load phase. } } return impl->match (a, t, hint); } #endif // BUILD2_BOOTSTRAP || LIBBUILD2_STATIC_BUILD recipe adhoc_cxx_rule:: apply (action a, target& t) const { return impl.load (memory_order_relaxed)->apply (a, t); } }