410 lines
13 KiB
C++
410 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 "db.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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void registerSuccessor(const Transaction & txn,
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const FSId & id1, const FSId & id2)
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{
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nixDB.setString(txn, dbSuccessors, id1, id2);
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}
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static FSId useSuccessor(const FSId & id)
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{
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string idSucc;
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if (nixDB.queryString(noTxn, dbSuccessors, id, idSucc)) {
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debug(format("successor %1% -> %2%") % (string) id % idSucc);
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return parseHash(idSucc);
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} else
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return id;
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}
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Strings pathsFromOutputs(const DerivationOutputs & ps)
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{
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Strings ss;
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for (DerivationOutputs::const_iterator i = ps.begin();
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i != ps.end(); i++)
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ss.push_back(i->first);
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return ss;
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}
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FSId normaliseNixExpr(FSId id, FSIdSet pending)
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{
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Nest nest(lvlTalkative,
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format("normalising nix expression %1%") % (string) id);
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/* Try to substitute $id$ by any known successors in order to
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speed up the rewrite process. */
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id = useSuccessor(id);
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/* Get the Nix expression. */
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NixExpr ne = parseNixExpr(termFromId(id));
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/* If this is a normal form (i.e., a closure) we are done. */
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if (ne.type == NixExpr::neClosure) return id;
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if (ne.type != NixExpr::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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/* Referencable paths (i.e., input and output paths). */
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StringSet 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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NixExpr nf;
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nf.type = NixExpr::neClosure;
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/* Parse the outputs. */
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for (DerivationOutputs::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 %1% in `%2%'") % (string) i->second % i->first);
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allPaths.insert(i->first);
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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(pathsFromOutputs(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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FSId id2 = useSuccessor(id);
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if (id2 != id) {
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NixExpr ne = parseNixExpr(termFromId(id2));
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debug(format("skipping build of %1%, someone beat us to it")
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% (string) id);
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if (ne.type != NixExpr::neClosure) abort();
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return id2;
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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 (FSIdSet::iterator i = ne.derivation.inputs.begin();
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i != ne.derivation.inputs.end(); i++)
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{
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FSId nf = normaliseNixExpr(*i, pending);
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realiseClosure(nf, pending);
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/* !!! nf should be a root of the garbage collector while we
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are building */
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NixExpr ne = parseNixExpr(termFromId(nf));
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if (ne.type != NixExpr::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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/* 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 we can expand all output
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paths from their ids. */
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bool fastBuild = true;
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for (DerivationOutputs::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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try {
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expandId(i->second, i->first, "/", pending);
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} catch (Error & e) {
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debug(format("fast build failed for `%1%': %2%")
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% i->first % e.what());
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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 (DerivationOutputs::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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string path = i->first;
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FSId id;
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if (queryPathId(path, id))
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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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msg(lvlChatty, format("building..."));
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runProgram(ne.derivation.builder, ne.derivation.args, env);
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msg(lvlChatty, format("build completed"));
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} else
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msg(lvlChatty, format("fast build succesful"));
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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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StringSet usedPaths;
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for (DerivationOutputs::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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{
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string path = i->first;
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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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Strings refPaths = filterReferences(path,
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Strings(allPaths.begin(), allPaths.end()));
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/* Construct a closure element for this output path. */
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ClosureElem elem;
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elem.id = i->second;
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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 (Strings::iterator j = refPaths.begin();
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j != refPaths.end(); j++)
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{
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string 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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StringSet donePaths;
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while (!usedPaths.empty()) {
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StringSet::iterator i = usedPaths.begin();
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string 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 (StringSet::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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StringSet::iterator j = donePaths.find(i->first);
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if (j == donePaths.end())
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debug(format("NOT referenced: `%1%'") % i->first);
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else
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debug(format("referenced: `%1%'") % i->first);
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}
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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 = unparseNixExpr(nf);
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msg(lvlVomit, format("normal form: %1%") % printTerm(nfTerm));
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FSId idNF = writeTerm(nfTerm, "-s-" + (string) id);
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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(nixDB);
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for (DerivationOutputs::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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registerPath(txn, i->first, i->second);
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registerSuccessor(txn, id, idNF);
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txn.commit();
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return idNF;
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}
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void realiseClosure(const FSId & id, FSIdSet pending)
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{
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Nest nest(lvlDebug,
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format("realising closure %1%") % (string) id);
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NixExpr ne = parseNixExpr(termFromId(id));
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if (ne.type != NixExpr::neClosure)
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throw Error(format("expected closure in %1%") % (string) id);
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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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expandId(i->second.id, i->first, "/", pending);
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}
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Strings nixExprPaths(const FSId & id)
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{
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Strings paths;
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NixExpr ne = parseNixExpr(termFromId(id));
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if (ne.type == NixExpr::neClosure) {
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for (StringSet::const_iterator i = ne.closure.roots.begin();
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i != ne.closure.roots.end(); i++)
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paths.push_back(*i);
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}
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else if (ne.type == NixExpr::neDerivation) {
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for (DerivationOutputs::iterator i = ne.derivation.outputs.begin();
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i != ne.derivation.outputs.end(); i++)
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paths.push_back(i->first);
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}
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else abort();
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return paths;
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}
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static void nixExprRequisitesSet(const FSId & id,
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bool includeExprs, bool includeSuccessors, StringSet & paths,
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FSIdSet & doneSet)
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{
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if (doneSet.find(id) != doneSet.end()) return;
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doneSet.insert(id);
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NixExpr ne = parseNixExpr(termFromId(id));
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if (ne.type == NixExpr::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 == NixExpr::neDerivation)
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for (FSIdSet::iterator i = ne.derivation.inputs.begin();
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i != ne.derivation.inputs.end(); i++)
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nixExprRequisitesSet(*i,
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includeExprs, includeSuccessors, paths, doneSet);
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else abort();
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if (includeExprs)
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paths.insert(expandId(id));
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string idSucc;
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if (includeSuccessors &&
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nixDB.queryString(noTxn, dbSuccessors, id, idSucc))
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nixExprRequisitesSet(parseHash(idSucc),
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includeExprs, includeSuccessors, paths, doneSet);
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}
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Strings nixExprRequisites(const FSId & id,
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bool includeExprs, bool includeSuccessors)
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{
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StringSet paths;
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FSIdSet doneSet;
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nixExprRequisitesSet(id, includeExprs, includeSuccessors, paths, doneSet);
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return Strings(paths.begin(), paths.end());
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}
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FSIds findGenerators(const FSIds & _ids)
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{
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FSIdSet ids(_ids.begin(), _ids.end());
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FSIds generators;
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/* !!! hack; for performance, we just look at the rhs of successor
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mappings, since we know that those are Nix expressions. */
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Strings sucs;
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nixDB.enumTable(noTxn, dbSuccessors, sucs);
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for (Strings::iterator i = sucs.begin();
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i != sucs.end(); i++)
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{
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string s;
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if (!nixDB.queryString(noTxn, dbSuccessors, *i, s)) continue;
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FSId id = parseHash(s);
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NixExpr ne;
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try {
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/* !!! should substitutes be used? */
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ne = parseNixExpr(termFromId(id));
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} catch (...) { /* !!! only catch parse errors */
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continue;
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}
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if (ne.type != NixExpr::neClosure) continue;
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bool okay = true;
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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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if (ids.find(i->second.id) == ids.end()) {
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okay = false;
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break;
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}
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if (!okay) continue;
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generators.push_back(id);
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}
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return generators;
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}
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