forked from lix-project/lix
404 lines
13 KiB
C++
404 lines
13 KiB
C++
#include <map>
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#include "normalise.hh"
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#include "references.hh"
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#include "exec.hh"
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#include "pathlocks.hh"
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#include "globals.hh"
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static Path useSuccessor(const Path & path)
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{
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string pathSucc;
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if (querySuccessor(path, pathSucc)) {
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debug(format("successor %1% -> %2%") % (string) path % pathSucc);
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return pathSucc;
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} else
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return path;
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}
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Path normaliseStoreExpr(const Path & _nePath, PathSet pending)
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{
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startNest(nest, lvlTalkative,
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format("normalising store expression in `%1%'") % (string) _nePath);
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/* Try to substitute the expression by any known successors in
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order to speed up the rewrite process. */
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Path nePath = useSuccessor(_nePath);
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/* Get the store expression. */
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StoreExpr ne = storeExprFromPath(nePath, pending);
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/* If this is a normal form (i.e., a closure) we are done. */
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if (ne.type == StoreExpr::neClosure) return nePath;
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if (ne.type != StoreExpr::neDerivation) abort();
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/* Otherwise, it's a derivation expression, and we have to build it to
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determine its normal form. */
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/* Some variables. */
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/* Input paths, with their closure elements. */
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ClosureElems inClosures;
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/* Referenceable paths (i.e., input and output paths). */
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PathSet allPaths;
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/* The environment to be passed to the builder. */
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Environment env;
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/* The result. */
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StoreExpr nf;
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nf.type = StoreExpr::neClosure;
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/* The outputs are referenceable paths. */
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for (PathSet::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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debug(format("building path `%1%'") % *i);
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allPaths.insert(*i);
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}
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/* Obtain locks on all output paths. The locks are automatically
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released when we exit this function or Nix crashes. */
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PathLocks outputLocks(ne.derivation.outputs);
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/* Now check again whether there is a successor. This is because
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another process may have started building in parallel. After
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it has finished and released the locks, we can (and should)
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reuse its results. (Strictly speaking the first successor
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check above can be omitted, but that would be less efficient.)
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Note that since we now hold the locks on the output paths, no
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other process can build this expression, so no further checks
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are necessary. */
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{
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Path nePath2 = useSuccessor(nePath);
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if (nePath != nePath2) {
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StoreExpr ne = storeExprFromPath(nePath2, pending);
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debug(format("skipping build of expression `%1%', someone beat us to it")
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% (string) nePath);
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if (ne.type != StoreExpr::neClosure) abort();
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outputLocks.setDeletion(true);
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return nePath2;
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}
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}
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/* Right platform? */
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if (ne.derivation.platform != thisSystem)
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throw Error(format("a `%1%' is required, but I am a `%2%'")
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% ne.derivation.platform % thisSystem);
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/* Realise inputs (and remember all input paths). */
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for (PathSet::iterator i = ne.derivation.inputs.begin();
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i != ne.derivation.inputs.end(); i++)
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{
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checkInterrupt();
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Path nfPath = normaliseStoreExpr(*i, pending);
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realiseClosure(nfPath, pending);
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/* !!! nfPath should be a root of the garbage collector while
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we are building */
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StoreExpr ne = storeExprFromPath(nfPath, pending);
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if (ne.type != StoreExpr::neClosure) abort();
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for (ClosureElems::iterator j = ne.closure.elems.begin();
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j != ne.closure.elems.end(); j++)
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{
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inClosures[j->first] = j->second;
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allPaths.insert(j->first);
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}
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}
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/* Most shells initialise PATH to some default (/bin:/usr/bin:...) when
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PATH is not set. We don't want this, so we fill it in with some dummy
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value. */
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env["PATH"] = "/path-not-set";
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/* Set HOME to a non-existing path to prevent certain programs from using
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/etc/passwd (or NIS, or whatever) to locate the home directory (for
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example, wget looks for ~/.wgetrc). I.e., these tools use /etc/passwd
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if HOME is not set, but they will just assume that the settings file
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they are looking for does not exist if HOME is set but points to some
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non-existing path. */
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env["HOME"] = "/homeless-shelter";
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/* Tell the builder where the Nix store is. Usually they
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shouldn't care, but this is useful for purity checking (e.g.,
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the compiler or linker might only want to accept paths to files
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in the store or in the build directory). */
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env["NIX_STORE"] = nixStore;
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/* Build the environment. */
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for (StringPairs::iterator i = ne.derivation.env.begin();
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i != ne.derivation.env.end(); i++)
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env[i->first] = i->second;
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/* We can skip running the builder if all output paths are already
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valid. */
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bool fastBuild = true;
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for (PathSet::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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if (!isValidPath(*i)) {
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fastBuild = false;
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break;
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}
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}
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if (!fastBuild) {
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/* If any of the outputs already exist but are not registered,
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delete them. */
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for (PathSet::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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Path path = *i;
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if (isValidPath(path))
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throw Error(format("obstructed build: path `%1%' exists") % path);
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if (pathExists(path)) {
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debug(format("removing unregistered path `%1%'") % path);
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deletePath(path);
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}
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}
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/* Run the builder. */
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startNest(nest2, lvlChatty,
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format("executing builder `%1%'") % ne.derivation.builder);
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runProgram(ne.derivation.builder, ne.derivation.args, env,
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nixLogDir + "/" + baseNameOf(nePath));
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printMsg(lvlChatty, format("builder completed"));
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nest2.close();
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} else
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printMsg(lvlChatty, format("fast build succesful"));
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startNest(nest3, lvlChatty, format("determining closure value"));
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/* Check whether the output paths were created, and grep each
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output path to determine what other paths it references. Also make all
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output paths read-only. */
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PathSet usedPaths;
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for (PathSet::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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Path path = *i;
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if (!pathExists(path))
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throw Error(format("path `%1%' does not exist") % path);
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nf.closure.roots.insert(path);
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makePathReadOnly(path);
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/* For this output path, find the references to other paths contained
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in it. */
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startNest(nest2, lvlChatty,
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format("scanning for store references in `%1%'") % ne.derivation.builder);
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Strings refPaths = filterReferences(path,
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Strings(allPaths.begin(), allPaths.end()));
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nest2.close();
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/* Construct a closure element for this output path. */
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ClosureElem elem;
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/* For each path referenced by this output path, add its id to the
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closure element and add the id to the `usedPaths' set (so that the
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elements referenced by *its* closure are added below). */
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for (Paths::iterator j = refPaths.begin();
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j != refPaths.end(); j++)
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{
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checkInterrupt();
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Path path = *j;
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elem.refs.insert(path);
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if (inClosures.find(path) != inClosures.end())
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usedPaths.insert(path);
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else if (ne.derivation.outputs.find(path) == ne.derivation.outputs.end())
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abort();
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}
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nf.closure.elems[path] = elem;
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}
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/* Close the closure. That is, for any referenced path, add the paths
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referenced by it. */
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PathSet donePaths;
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while (!usedPaths.empty()) {
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checkInterrupt();
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PathSet::iterator i = usedPaths.begin();
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Path path = *i;
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usedPaths.erase(i);
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if (donePaths.find(path) != donePaths.end()) continue;
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donePaths.insert(path);
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ClosureElems::iterator j = inClosures.find(path);
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if (j == inClosures.end()) abort();
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nf.closure.elems[path] = j->second;
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for (PathSet::iterator k = j->second.refs.begin();
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k != j->second.refs.end(); k++)
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usedPaths.insert(*k);
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}
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/* For debugging, print out the referenced and unreferenced paths. */
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for (ClosureElems::iterator i = inClosures.begin();
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i != inClosures.end(); i++)
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{
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PathSet::iterator j = donePaths.find(i->first);
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if (j == donePaths.end())
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debug(format("unreferenced input: `%1%'") % i->first);
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else
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debug(format("referenced input: `%1%'") % i->first);
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}
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nest3.close();
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/* Write the normal form. This does not have to occur in the
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transaction below because writing terms is idem-potent. */
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ATerm nfTerm = unparseStoreExpr(nf);
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printMsg(lvlVomit, format("normal form: %1%") % atPrint(nfTerm));
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Path nfPath = writeTerm(nfTerm, "-s");
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/* Register each outpat path, and register the normal form. This
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is wrapped in one database transaction to ensure that if we
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crash, either everything is registered or nothing is. This is
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for recoverability: unregistered paths in the store can be
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deleted arbitrarily, while registered paths can only be deleted
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by running the garbage collector. */
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Transaction txn;
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createStoreTransaction(txn);
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for (PathSet::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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registerValidPath(txn, *i);
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registerSuccessor(txn, nePath, nfPath);
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txn.commit();
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/* It is now safe to delete the lock files, since all future
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lockers will see the successor; they will not create new lock
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files with the same names as the old (unlinked) lock files. */
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outputLocks.setDeletion(true);
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return nfPath;
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}
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void realiseClosure(const Path & nePath, PathSet pending)
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{
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startNest(nest, lvlDebug, format("realising closure `%1%'") % nePath);
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StoreExpr ne = storeExprFromPath(nePath, pending);
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if (ne.type != StoreExpr::neClosure)
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throw Error(format("expected closure in `%1%'") % nePath);
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for (ClosureElems::const_iterator i = ne.closure.elems.begin();
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i != ne.closure.elems.end(); i++)
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ensurePath(i->first, pending);
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}
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void ensurePath(const Path & path, PathSet pending)
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{
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/* If the path is already valid, we're done. */
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if (isValidPath(path)) return;
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if (pending.find(path) != pending.end())
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throw Error(format(
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"path `%1%' already being realised (possible substitute cycle?)")
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% path);
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pending.insert(path);
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/* Otherwise, try the substitutes. */
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Paths subPaths = querySubstitutes(path);
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for (Paths::iterator i = subPaths.begin();
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i != subPaths.end(); i++)
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{
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checkInterrupt();
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try {
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Path nf = normaliseStoreExpr(*i, pending);
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realiseClosure(nf, pending);
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if (isValidPath(path)) return;
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throw Error(format("substitute failed to produce expected output path"));
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} catch (Error & e) {
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printMsg(lvlTalkative,
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format("building of substitute `%1%' for `%2%' failed: %3%")
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% *i % path % e.what());
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}
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}
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throw Error(format("path `%1%' is required, "
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"but there are no (successful) substitutes") % path);
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}
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StoreExpr storeExprFromPath(const Path & path, PathSet pending)
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{
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ensurePath(path, pending);
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ATerm t = ATreadFromNamedFile(path.c_str());
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if (!t) throw Error(format("cannot read aterm from `%1%'") % path);
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return parseStoreExpr(t);
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}
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PathSet storeExprRoots(const Path & nePath)
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{
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PathSet paths;
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StoreExpr ne = storeExprFromPath(nePath);
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if (ne.type == StoreExpr::neClosure)
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paths.insert(ne.closure.roots.begin(), ne.closure.roots.end());
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else if (ne.type == StoreExpr::neDerivation)
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paths.insert(ne.derivation.outputs.begin(),
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ne.derivation.outputs.end());
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else abort();
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return paths;
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}
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static void requisitesWorker(const Path & nePath,
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bool includeExprs, bool includeSuccessors,
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PathSet & paths, PathSet & doneSet)
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{
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checkInterrupt();
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if (doneSet.find(nePath) != doneSet.end()) return;
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doneSet.insert(nePath);
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StoreExpr ne = storeExprFromPath(nePath);
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if (ne.type == StoreExpr::neClosure)
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for (ClosureElems::iterator i = ne.closure.elems.begin();
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i != ne.closure.elems.end(); i++)
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paths.insert(i->first);
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else if (ne.type == StoreExpr::neDerivation)
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for (PathSet::iterator i = ne.derivation.inputs.begin();
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i != ne.derivation.inputs.end(); i++)
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requisitesWorker(*i,
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includeExprs, includeSuccessors, paths, doneSet);
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else abort();
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if (includeExprs) paths.insert(nePath);
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string nfPath;
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if (includeSuccessors && (nfPath = useSuccessor(nePath)) != nePath)
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requisitesWorker(nfPath, includeExprs, includeSuccessors,
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paths, doneSet);
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}
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PathSet storeExprRequisites(const Path & nePath,
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bool includeExprs, bool includeSuccessors)
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{
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PathSet paths;
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PathSet doneSet;
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requisitesWorker(nePath, includeExprs, includeSuccessors,
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paths, doneSet);
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return paths;
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}
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