nix search: Add a cache

The package list is now cached in
~/.cache/nix/package-search.json. This gives a substantial speedup to
"nix search" queries. For example (on an SSD):

First run: (no package search cache, cold page cache)

  $ time nix search blender
  Attribute name: nixpkgs.blender
  Package name: blender
  Version: 2.78c
  Description: 3D Creation/Animation/Publishing System

  real    0m6.516s

Second run: (package search cache populated)

  $ time nix search blender
  Attribute name: nixpkgs.blender
  Package name: blender
  Version: 2.78c
  Description: 3D Creation/Animation/Publishing System

  real    0m0.143s
This commit is contained in:
Eelco Dolstra 2017-07-26 17:21:46 +02:00
parent 4c9ff89c26
commit 57b9505731
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
3 changed files with 92 additions and 20 deletions

View file

@ -50,20 +50,22 @@ template<> void toJSON<std::nullptr_t>(std::ostream & str, const std::nullptr_t
JSONWriter::JSONWriter(std::ostream & str, bool indent)
: state(new JSONState(str, indent))
{
state->stack.push_back(this);
state->stack++;
}
JSONWriter::JSONWriter(JSONState * state)
: state(state)
{
state->stack.push_back(this);
state->stack++;
}
JSONWriter::~JSONWriter()
{
if (state) {
assertActive();
state->stack.pop_back();
if (state->stack.empty()) delete state;
state->stack--;
if (state->stack == 0) delete state;
}
}
void JSONWriter::comma()
@ -121,9 +123,11 @@ void JSONObject::open()
JSONObject::~JSONObject()
{
if (state) {
state->depth--;
if (state->indent && !first) indent();
state->str << "}";
}
}
void JSONObject::attr(const std::string & s)

View file

@ -21,11 +21,11 @@ protected:
std::ostream & str;
bool indent;
size_t depth = 0;
std::vector<JSONWriter *> stack;
size_t stack = 0;
JSONState(std::ostream & str, bool indent) : str(str), indent(indent) { }
~JSONState()
{
assert(stack.empty());
assert(stack == 0);
}
};
@ -41,7 +41,7 @@ protected:
void assertActive()
{
assert(!state->stack.empty() && state->stack.back() == this);
assert(state->stack != 0);
}
void comma();
@ -117,6 +117,14 @@ public:
open();
}
JSONObject(const JSONObject & obj) = delete;
JSONObject(JSONObject && obj)
: JSONWriter(obj.state)
{
obj.state = 0;
}
~JSONObject();
template<typename T>

View file

@ -6,8 +6,10 @@
#include "get-drvs.hh"
#include "common-args.hh"
#include "json.hh"
#include "json-to-value.hh"
#include <regex>
#include <fstream>
using namespace nix;
@ -25,9 +27,23 @@ struct CmdSearch : SourceExprCommand, MixJSON
{
std::string re;
bool writeCache = true;
bool useCache = true;
CmdSearch()
{
expectArg("regex", &re, true);
mkFlag()
.longName("update-cache")
.shortName('u')
.description("update the package search cache")
.handler([&](Strings ss) { writeCache = true; useCache = false; });
mkFlag()
.longName("no-cache")
.description("do not use or update the package search cache")
.handler([&](Strings ss) { writeCache = false; useCache = false; });
}
std::string name() override
@ -48,15 +64,18 @@ struct CmdSearch : SourceExprCommand, MixJSON
auto state = getEvalState();
std::function<void(Value *, std::string, bool)> doExpr;
bool first = true;
auto jsonOut = json ? std::make_unique<JSONObject>(std::cout, true) : nullptr;
auto sToplevel = state->symbols.create("_toplevel");
auto sRecurse = state->symbols.create("recurseForDerivations");
doExpr = [&](Value * v, std::string attrPath, bool toplevel) {
bool fromCache = false;
std::function<void(Value *, std::string, bool, JSONObject *)> doExpr;
doExpr = [&](Value * v, std::string attrPath, bool toplevel, JSONObject * cache) {
debug("at attribute %s", attrPath);
try {
@ -115,23 +134,41 @@ struct CmdSearch : SourceExprCommand, MixJSON
hilite(description, descriptionMatch));
}
}
if (cache) {
cache->attr("type", "derivation");
cache->attr("name", drv.queryName());
cache->attr("system", drv.querySystem());
if (description != "") {
auto meta(cache->object("meta"));
meta.attr("description", description);
}
}
}
else if (v->type == tAttrs) {
if (!toplevel) {
auto attrs = v->attrs;
Bindings::iterator j = attrs->find(state->symbols.create("recurseForDerivations"));
if (j == attrs->end() || !state->forceBool(*j->value, *j->pos)) return;
Bindings::iterator j = attrs->find(sRecurse);
if (j == attrs->end() || !state->forceBool(*j->value, *j->pos)) {
debug("skip attribute %s", attrPath);
return;
}
}
bool toplevel2 = false;
if (!fromCache) {
Bindings::iterator j = v->attrs->find(sToplevel);
bool toplevel2 = j != v->attrs->end() && state->forceBool(*j->value, *j->pos);
toplevel2 = j != v->attrs->end() && state->forceBool(*j->value, *j->pos);
}
for (auto & i : *v->attrs) {
auto cache2 =
cache ? std::make_unique<JSONObject>(cache->object(i.name)) : nullptr;
doExpr(i.value,
attrPath == "" ? (std::string) i.name : attrPath + "." + (std::string) i.name,
toplevel2);
toplevel2 || fromCache, cache2 ? cache2.get() : nullptr);
}
}
@ -144,7 +181,30 @@ struct CmdSearch : SourceExprCommand, MixJSON
}
};
doExpr(getSourceExpr(*state), "", true);
Path jsonCacheFileName = getCacheDir() + "/nix/package-search.json";
if (useCache && pathExists(jsonCacheFileName)) {
Value vRoot;
parseJSON(*state, readFile(jsonCacheFileName), vRoot);
fromCache = true;
doExpr(&vRoot, "", true, nullptr);
}
else {
Path tmpFile = fmt("%s.tmp.%d", jsonCacheFileName, getpid());
std::ofstream jsonCacheFile(tmpFile);
auto cache = writeCache ? std::make_unique<JSONObject>(jsonCacheFile, false) : nullptr;
doExpr(getSourceExpr(*state), "", true, cache.get());
if (rename(tmpFile.c_str(), jsonCacheFileName.c_str()) == -1)
throw SysError("cannot rename %s to %s", tmpFile, jsonCacheFileName);
}
}
};