diff options
Diffstat (limited to 'src/libstore/derivations.hh')
| -rw-r--r-- | src/libstore/derivations.hh | 187 |
1 files changed, 168 insertions, 19 deletions
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh index 68c53c1ff..b1cb68194 100644 --- a/src/libstore/derivations.hh +++ b/src/libstore/derivations.hh @@ -4,8 +4,10 @@ #include "types.hh" #include "hash.hh" #include "content-address.hh" +#include "sync.hh" #include <map> +#include <variant> namespace nix { @@ -13,20 +15,90 @@ namespace nix { /* Abstract syntax of derivations. */ -struct DerivationOutput +/* The traditional non-fixed-output derivation type. */ +struct DerivationOutputInputAddressed { StorePath path; - std::optional<FixedOutputHash> hash; /* hash used for expected hash computation */ +}; + +/* Fixed-output derivations, whose output paths are content addressed + according to that fixed output. */ +struct DerivationOutputCAFixed +{ + FixedOutputHash hash; /* hash used for expected hash computation */ + StorePath path(const Store & store, std::string_view drvName, std::string_view outputName) const; +}; + +/* Floating-output derivations, whose output paths are content addressed, but + not fixed, and so are dynamically calculated from whatever the output ends + up being. */ +struct DerivationOutputCAFloating +{ + /* information used for expected hash computation */ + FileIngestionMethod method; + HashType hashType; +}; + +/* Input-addressed output which depends on a (CA) derivation whose hash isn't + * known atm + */ +struct DerivationOutputDeferred {}; + +struct DerivationOutput +{ + std::variant< + DerivationOutputInputAddressed, + DerivationOutputCAFixed, + DerivationOutputCAFloating, + DerivationOutputDeferred + > output; + + /* Note, when you use this function you should make sure that you're passing + the right derivation name. When in doubt, you should use the safer + interface provided by BasicDerivation::outputsAndOptPaths */ + std::optional<StorePath> path(const Store & store, std::string_view drvName, std::string_view outputName) const; }; typedef std::map<string, DerivationOutput> DerivationOutputs; +/* These are analogues to the previous DerivationOutputs data type, but they + also contains, for each output, the (optional) store path in which it would + be written. To calculate values of these types, see the corresponding + functions in BasicDerivation */ +typedef std::map<string, std::pair<DerivationOutput, std::optional<StorePath>>> + DerivationOutputsAndOptPaths; + /* For inputs that are sub-derivations, we specify exactly which output IDs we are interested in. */ typedef std::map<StorePath, StringSet> DerivationInputs; typedef std::map<string, string> StringPairs; +enum struct DerivationType : uint8_t { + InputAddressed, + DeferredInputAddressed, + CAFixed, + CAFloating, +}; + +/* Do the outputs of the derivation have paths calculated from their content, + or from the derivation itself? */ +bool derivationIsCA(DerivationType); + +/* Is the content of the outputs fixed a-priori via a hash? Never true for + non-CA derivations. */ +bool derivationIsFixed(DerivationType); + +/* Is the derivation impure and needs to access non-deterministic resources, or + pure and can be sandboxed? Note that whether or not we actually sandbox the + derivation is controlled separately. Never true for non-CA derivations. */ +bool derivationIsImpure(DerivationType); + +/* Does the derivation knows its own output paths? + * Only true when there's no floating-ca derivation involved in the closure. + */ +bool derivationHasKnownOutputPaths(DerivationType); + struct BasicDerivation { DerivationOutputs outputs; /* keyed on symbolic IDs */ @@ -35,24 +107,25 @@ struct BasicDerivation Path builder; Strings args; StringPairs env; + std::string name; - BasicDerivation() { } + BasicDerivation() = default; virtual ~BasicDerivation() { }; - /* Return the path corresponding to the output identifier `id' in - the given derivation. */ - const StorePath & findOutput(const std::string & id) const; - bool isBuiltin() const; /* Return true iff this is a fixed-output derivation. */ - bool isFixedOutput() const; - - /* Return the output paths of a derivation. */ - StorePathSet outputPaths() const; + DerivationType type() const; /* Return the output names of a derivation. */ StringSet outputNames() const; + + /* Calculates the maps that contains all the DerivationOutputs, but + augmented with knowledge of the Store paths they would be written + into. */ + DerivationOutputsAndOptPaths outputsAndOptPaths(const Store & store) const; + + static std::string_view nameFromPath(const StorePath & storePath); }; struct Derivation : BasicDerivation @@ -63,7 +136,17 @@ struct Derivation : BasicDerivation std::string unparse(const Store & store, bool maskOutputs, std::map<std::string, StringSet> * actualInputs = nullptr) const; - Derivation() { } + /* Return the underlying basic derivation but with these changes: + + 1. Input drvs are emptied, but the outputs of them that were used are + added directly to input sources. + + 2. Input placeholders are replaced with realized input store paths. */ + std::optional<BasicDerivation> tryResolve(Store & store); + + Derivation() = default; + Derivation(const BasicDerivation & bd) : BasicDerivation(bd) { } + Derivation(BasicDerivation && bd) : BasicDerivation(std::move(bd)) { } }; @@ -72,30 +155,96 @@ class Store; enum RepairFlag : bool { NoRepair = false, Repair = true }; /* Write a derivation to the Nix store, and return its path. */ -StorePath writeDerivation(ref<Store> store, - const Derivation & drv, std::string_view name, RepairFlag repair = NoRepair); +StorePath writeDerivation(Store & store, + const Derivation & drv, + RepairFlag repair = NoRepair, + bool readOnly = false); /* Read a derivation from a file. */ -Derivation readDerivation(const Store & store, const Path & drvPath); +Derivation parseDerivation(const Store & store, std::string && s, std::string_view name); // FIXME: remove bool isDerivation(const string & fileName); -Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs); +/* Calculate the name that will be used for the store path for this + output. + + This is usually <drv-name>-<output-name>, but is just <drv-name> when + the output name is "out". */ +std::string outputPathName(std::string_view drvName, std::string_view outputName); + +// known CA drv's output hashes, current just for fixed-output derivations +// whose output hashes are always known since they are fixed up-front. +typedef std::map<std::string, Hash> CaOutputHashes; + +struct DeferredHash { Hash hash; }; + +typedef std::variant< + Hash, // regular DRV normalized hash + CaOutputHashes, // Fixed-output derivation hashes + DeferredHash // Deferred hashes for floating outputs drvs and their dependencies +> DrvHashModulo; + +/* Returns hashes with the details of fixed-output subderivations + expunged. + + A fixed-output derivation is a derivation whose outputs have a + specified content hash and hash algorithm. (Currently they must have + exactly one output (`out'), which is specified using the `outputHash' + and `outputHashAlgo' attributes, but the algorithm doesn't assume + this.) We don't want changes to such derivations to propagate upwards + through the dependency graph, changing output paths everywhere. + + For instance, if we change the url in a call to the `fetchurl' + function, we do not want to rebuild everything depending on it---after + all, (the hash of) the file being downloaded is unchanged. So the + *output paths* should not change. On the other hand, the *derivation + paths* should change to reflect the new dependency graph. + + For fixed-output derivations, this returns a map from the name of + each output to its hash, unique up to the output's contents. + + For regular derivations, it returns a single hash of the derivation + ATerm, after subderivations have been likewise expunged from that + derivation. + */ +DrvHashModulo hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutputs); + +/* + Return a map associating each output to a hash that uniquely identifies its + derivation (modulo the self-references). + */ +std::map<std::string, Hash> staticOutputHashes(Store& store, const Derivation& drv); /* Memoisation of hashDerivationModulo(). */ -typedef std::map<StorePath, Hash> DrvHashes; +typedef std::map<StorePath, DrvHashModulo> DrvHashes; -extern DrvHashes drvHashes; // FIXME: global, not thread-safe +// FIXME: global, though at least thread-safe. +extern Sync<DrvHashes> drvHashes; bool wantOutput(const string & output, const std::set<string> & wanted); struct Source; struct Sink; -Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv); +Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name); void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv); +/* This creates an opaque and almost certainly unique string + deterministically from the output name. + + It is used as a placeholder to allow derivations to refer to their + own outputs without needing to use the hash of a derivation in + itself, making the hash near-impossible to calculate. */ std::string hashPlaceholder(const std::string & outputName); +/* This creates an opaque and almost certainly unique string + deterministically from a derivation path and output name. + + It is used as a placeholder to allow derivations to refer to + content-addressed paths whose content --- and thus the path + themselves --- isn't yet known. This occurs when a derivation has a + dependency which is a CA derivation. */ +std::string downstreamPlaceholder(const Store & store, const StorePath & drvPath, std::string_view outputName); + } |