* Refactorings.

src/normalise.cc

@@ -0,0 +1,265 @@
+#include <map>
+
+#include "normalise.hh"
+#include "references.hh"
+#include "db.hh"
+#include "exec.hh"
+#include "globals.hh"
+
+
+void registerSuccessor(const FSId & id1, const FSId & id2)
+{
+    setDB(nixDB, dbSuccessors, id1, id2);
+}
+
+
+static FSId storeSuccessor(const FSId & id1, ATerm sc)
+{
+    FSId id2 = writeTerm(sc, "-s-" + (string) id1);
+    registerSuccessor(id1, id2);
+    return id2;
+}
+
+
+typedef set<FSId> FSIdSet;
+
+
+Slice normaliseFState(FSId id)
+{
+    debug(format("normalising fstate %1%") % (string) id);
+    Nest nest(true);
+
+    /* Try to substitute $id$ by any known successors in order to
+       speed up the rewrite process. */
+    string idSucc;
+    while (queryDB(nixDB, dbSuccessors, id, idSucc)) {
+        debug(format("successor %1% -> %2%") % (string) id % idSucc);
+        id = parseHash(idSucc);
+    }
+
+    /* Get the fstate expression. */
+    FState fs = parseFState(termFromId(id));
+
+    /* It this is a normal form (i.e., a slice) we are done. */
+    if (fs.type == FState::fsSlice) return fs.slice;
+    
+    /* Otherwise, it's a derivation. */
+
+    /* Right platform? */
+    if (fs.derive.platform != thisSystem)
+        throw Error(format("a `%1%' is required, but I am a `%2%'")
+            % fs.derive.platform % thisSystem);
+        
+    /* Realise inputs (and remember all input paths). */
+    typedef map<string, SliceElem> ElemMap;
+
+    ElemMap inMap;
+
+    for (FSIds::iterator i = fs.derive.inputs.begin();
+         i != fs.derive.inputs.end(); i++) {
+        Slice slice = normaliseFState(*i);
+        realiseSlice(slice);
+
+        for (SliceElems::iterator j = slice.elems.begin();
+             j != slice.elems.end(); j++)
+            inMap[j->path] = *j;
+    }
+
+    Strings inPaths;
+    for (ElemMap::iterator i = inMap.begin(); i != inMap.end(); i++)
+        inPaths.push_back(i->second.path);
+
+    /* Build the environment. */
+    Environment env;
+    for (StringPairs::iterator i = fs.derive.env.begin();
+         i != fs.derive.env.end(); i++)
+        env[i->first] = i->second;
+
+    /* Parse the outputs. */
+    typedef map<string, FSId> OutPaths;
+    OutPaths outPaths;
+    for (DeriveOutputs::iterator i = fs.derive.outputs.begin();
+         i != fs.derive.outputs.end(); i++)
+    {
+        debug(format("building %1% in %2%") % (string) i->second % i->first);
+        outPaths[i->first] = i->second;
+        inPaths.push_back(i->first);
+    }
+
+    /* We can skip running the builder if we can expand all output
+       paths from their ids. */
+    bool fastBuild = false;
+#if 0
+    for (OutPaths::iterator i = outPaths.begin(); 
+         i != outPaths.end(); i++)
+    {
+        try {
+            expandId(i->second, i->first);
+        } catch (...) {
+            fastBuild = false;
+            break;
+        }
+    }
+#endif
+
+    if (!fastBuild) {
+
+        /* Check that none of the outputs exist. */
+        for (OutPaths::iterator i = outPaths.begin(); 
+             i != outPaths.end(); i++)
+            if (pathExists(i->first))
+                throw Error(format("path `%1%' exists") % i->first);
+
+        /* Run the builder. */
+        debug(format("building..."));
+        runProgram(fs.derive.builder, env);
+        debug(format("build completed"));
+        
+    } else
+        debug(format("skipping build"));
+
+    /* Check whether the output paths were created, and register each
+       one. */
+    FSIdSet used;
+    for (OutPaths::iterator i = outPaths.begin(); 
+         i != outPaths.end(); i++)
+    {
+        string path = i->first;
+        if (!pathExists(path))
+            throw Error(format("path `%1%' does not exist") % path);
+        registerPath(path, i->second);
+        fs.slice.roots.push_back(i->second);
+
+        Strings refs = filterReferences(path, inPaths);
+
+        SliceElem elem;
+        elem.path = path;
+        elem.id = i->second;
+
+        for (Strings::iterator j = refs.begin(); j != refs.end(); j++) {
+            ElemMap::iterator k;
+            OutPaths::iterator l;
+            if ((k = inMap.find(*j)) != inMap.end()) {
+                elem.refs.push_back(k->second.id);
+                used.insert(k->second.id);
+                for (FSIds::iterator m = k->second.refs.begin();
+                     m != k->second.refs.end(); m++)
+                    used.insert(*m);
+            } else if ((l = outPaths.find(*j)) != outPaths.end()) {
+                elem.refs.push_back(l->second);
+                used.insert(l->second);
+            } else 
+                throw Error(format("unknown referenced path `%1%'") % *j);
+        }
+
+        fs.slice.elems.push_back(elem);
+    }
+
+    for (ElemMap::iterator i = inMap.begin();
+         i != inMap.end(); i++)
+    {
+        FSIdSet::iterator j = used.find(i->second.id);
+        if (j == used.end())
+            debug(format("NOT referenced: `%1%'") % i->second.path);
+        else {
+            debug(format("referenced: `%1%'") % i->second.path);
+            fs.slice.elems.push_back(i->second);
+        }
+    }
+
+    fs.type = FState::fsSlice;
+    ATerm nf = unparseFState(fs);
+    debug(format("normal form: %1%") % printTerm(nf));
+    storeSuccessor(id, nf);
+
+    return fs.slice;
+}
+
+
+void realiseSlice(const Slice & slice)
+{
+    debug(format("realising slice"));
+    Nest nest(true);
+
+    /* Perhaps all paths already contain the right id? */
+
+    bool missing = false;
+    for (SliceElems::const_iterator i = slice.elems.begin();
+         i != slice.elems.end(); i++)
+    {
+        SliceElem elem = *i;
+        string id;
+        if (!queryDB(nixDB, dbPath2Id, elem.path, id)) {
+            if (pathExists(elem.path))
+                throw Error(format("path `%1%' obstructed") % elem.path);
+            missing = true;
+            break;
+        }
+        if (parseHash(id) != elem.id)
+            throw Error(format("path `%1%' obstructed") % elem.path);
+    }
+
+    if (!missing) {
+        debug(format("already installed"));
+        return;
+    }
+
+    /* For each element, expand its id at its path. */
+    for (SliceElems::const_iterator i = slice.elems.begin();
+         i != slice.elems.end(); i++)
+    {
+        SliceElem elem = *i;
+        debug(format("expanding %1% in %2%") % (string) elem.id % elem.path);
+        expandId(elem.id, elem.path);
+    }
+}
+
+
+Strings fstatePaths(const FSId & id, bool normalise)
+{
+    Strings paths;
+
+    FState fs;
+
+    if (normalise) {
+        fs.slice = normaliseFState(id);
+        fs.type = FState::fsSlice;
+    } else
+        fs = parseFState(termFromId(id));
+
+    if (fs.type == FState::fsSlice) {
+        /* !!! fix complexity */
+        for (FSIds::const_iterator i = fs.slice.roots.begin();
+             i != fs.slice.roots.end(); i++)
+            for (SliceElems::const_iterator j = fs.slice.elems.begin();
+                 j != fs.slice.elems.end(); j++)
+                if (*i == j->id) paths.push_back(j->path);
+    }
+
+    else if (fs.type == FState::fsDerive) {
+        for (DeriveOutputs::iterator i = fs.derive.outputs.begin();
+             i != fs.derive.outputs.end(); i++)
+            paths.push_back(i->first);
+    }
+    
+    else abort();
+
+    return paths;
+}
+
+
+StringSet fstateRefs(const FSId & id)
+{
+    StringSet paths;
+    Slice slice = normaliseFState(id);
+    for (SliceElems::const_iterator i = slice.elems.begin();
+         i != slice.elems.end(); i++)
+        paths.insert(i->path);
+    return paths;
+}
+
+
+void findGenerators(const FSIds & ids)
+{
+    
+}