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Diffstat (limited to 'libbuild2/rule-adhoc-cxx.cxx')
| -rw-r--r-- | libbuild2/rule-adhoc-cxx.cxx | 640 |
1 files changed, 640 insertions, 0 deletions
diff --git a/libbuild2/rule-adhoc-cxx.cxx b/libbuild2/rule-adhoc-cxx.cxx new file mode 100644 index 0000000..098cf4f --- /dev/null +++ b/libbuild2/rule-adhoc-cxx.cxx @@ -0,0 +1,640 @@ +// 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, '}'); + } + + // 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_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' + << 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); + } + + recipe adhoc_cxx_rule:: + apply (action a, target& t) const + { + return impl.load (memory_order_relaxed)->apply (a, t); + } +} |