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Use a more space/time-efficient representation for the eval cache

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This commit is contained in:
Eelco Dolstra 2020-04-17 23:04:21 +02:00
parent bdb3226607
commit aaa109565e
6 changed files with 102 additions and 51 deletions
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1
src/libexpr/eval.cc
View file

@ -351,6 +351,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
, sOutputHashMode(symbols.create("outputHashMode"))
, sDescription(symbols.create("description"))
, sSelf(symbols.create("self"))
, sEpsilon(symbols.create(""))
, repair(NoRepair)
, store(store)
, baseEnv(allocEnv(128))

2
src/libexpr/eval.hh
View file

@ -75,7 +75,7 @@ public:
sFile, sLine, sColumn, sFunctor, sToString,
sRight, sWrong, sStructuredAttrs, sBuilder, sArgs,
sOutputHash, sOutputHashAlgo, sOutputHashMode,
sDescription, sSelf;
sDescription, sSelf, sEpsilon;
Symbol sDerivationNix;
/* If set, force copying files to the Nix store even if they

2
src/libstore/local-store.cc
View file

@ -588,7 +588,7 @@ uint64_t LocalStore::addValidPath(State & state,
(concatStringsSep(" ", info.sigs), !info.sigs.empty())
(info.ca, !info.ca.empty())
.exec();
uint64_t id = sqlite3_last_insert_rowid(state.db);
uint64_t id = state.db.getLastInsertedRowId();
/* If this is a derivation, then store the derivation outputs in
the database. This is useful for the garbage collector: it can

5
src/libstore/sqlite.cc
View file

@ -61,6 +61,11 @@ void SQLite::exec(const std::string & stmt)
});
}
uint64_t SQLite::getLastInsertedRowId()
{
return sqlite3_last_insert_rowid(db);
}
void SQLiteStmt::create(sqlite3 * db, const string & sql)
{
checkInterrupt();

2
src/libstore/sqlite.hh
View file

@ -26,6 +26,8 @@ struct SQLite
void isCache();
void exec(const std::string & stmt);
uint64_t getLastInsertedRowId();
};
/* RAII wrapper to create and destroy SQLite prepared statements. */

141
src/nix/flake.cc
View file

@ -672,13 +672,17 @@ struct CmdFlakeArchive : FlakeCommand, MixJSON, MixDryRun
// FIXME: inefficient representation of attrs
static const char * schema = R"sql(
create table if not exists Attributes (
attrPath text primary key,
parent integer not null,
name text,
type integer not null,
value text not null
value text,
primary key (parent, name)
);
)sql";
enum AttrType {
Placeholder = 0,
// FIXME: distinguish between full / partial attrsets
Attrs = 1,
String = 2,
};
@ -690,8 +694,14 @@ struct AttrDb
SQLite db;
SQLiteStmt insertAttribute;
SQLiteStmt queryAttribute;
SQLiteStmt queryAttributes;
};
struct placeholder_t {};
typedef uint64_t AttrId;
typedef std::pair<AttrId, Symbol> AttrKey;
typedef std::variant<std::vector<Symbol>, std::string, placeholder_t> AttrValue;
std::unique_ptr<Sync<State>> _state;
AttrDb(const Fingerprint & fingerprint)
@ -709,57 +719,78 @@ struct AttrDb
state->db.exec(schema);
state->insertAttribute.create(state->db,
"insert or replace into Attributes(attrPath, type, value) values (?, ?, ?)");
"insert or replace into Attributes(parent, name, type, value) values (?, ?, ?, ?)");
state->queryAttribute.create(state->db,
"select type, value from Attributes where attrPath = ?");
"select rowid, type, value from Attributes where parent = ? and name = ?");
state->queryAttributes.create(state->db,
"select name from Attributes where parent = ?");
}
void setAttr(
const std::vector<Symbol> & attrPath,
AttrId setAttr(
AttrKey key,
const std::vector<Symbol> & attrs)
{
auto state(_state->lock());
state->insertAttribute.use()
(concatStringsSep(".", attrPath))
(key.first)
(key.second)
(AttrType::Attrs)
(concatStringsSep("\n", attrs)).exec();
(0, false).exec();
AttrId rowId = state->db.getLastInsertedRowId();
assert(rowId);
for (auto & attr : attrs)
state->insertAttribute.use()
(rowId)
(attr)
(AttrType::Placeholder)
(0, false).exec();
return rowId;
}
void setAttr(
const std::vector<Symbol> & attrPath,
AttrId setAttr(
AttrKey key,
std::string_view s)
{
auto state(_state->lock());
state->insertAttribute.use()
(concatStringsSep(".", attrPath))
(key.first)
(key.second)
(AttrType::String)
(s).exec();
return state->db.getLastInsertedRowId();
}
typedef std::variant<std::vector<Symbol>, std::string> AttrValue;
std::optional<AttrValue> getAttr(
const std::vector<Symbol> & attrPath,
std::optional<std::pair<AttrId, AttrValue>> getAttr(
AttrKey key,
SymbolTable & symbols)
{
auto state(_state->lock());
auto queryAttribute(state->queryAttribute.use()
(concatStringsSep(".", attrPath)));
auto queryAttribute(state->queryAttribute.use()(key.first)(key.second));
if (!queryAttribute.next()) return {};
auto type = (AttrType) queryAttribute.getInt(0);
auto rowId = (AttrType) queryAttribute.getInt(0);
auto type = (AttrType) queryAttribute.getInt(1);
if (type == AttrType::Attrs) {
if (type == AttrType::Placeholder)
return {{rowId, placeholder_t()}};
else if (type == AttrType::Attrs) {
// FIXME: expensive, should separate this out.
std::vector<Symbol> attrs;
for (auto & s : tokenizeString<std::vector<std::string>>(queryAttribute.getStr(1), "\n"))
attrs.push_back(symbols.create(s));
return attrs;
auto queryAttributes(state->queryAttributes.use()(rowId));
while (queryAttributes.next())
attrs.push_back(symbols.create(queryAttributes.getStr(0)));
return {{rowId, attrs}};
} else if (type == AttrType::String) {
return queryAttribute.getStr(1);
return {{rowId, queryAttribute.getStr(2)}};
} else
throw Error("unexpected type in evaluation cache");
}
@ -803,19 +834,31 @@ struct AttrCursor : std::enable_shared_from_this<AttrCursor>
typedef std::optional<std::pair<std::shared_ptr<AttrCursor>, Symbol>> Parent;
Parent parent;
RootValue _value;
std::optional<AttrDb::AttrValue> cachedValue;
std::optional<std::pair<AttrDb::AttrId, AttrDb::AttrValue>> cachedValue;
AttrCursor(
ref<AttrRoot> root,
Parent parent,
Value * value = nullptr,
std::optional<AttrDb::AttrValue> && cachedValue = {})
std::optional<std::pair<AttrDb::AttrId, AttrDb::AttrValue>> && cachedValue = {})
: root(root), parent(parent), cachedValue(std::move(cachedValue))
{
if (value)
_value = allocRootValue(value);
}
AttrDb::AttrKey getAttrKey()
{
if (!parent)
return {0, root->state.sEpsilon};
if (!parent->first->cachedValue) {
parent->first->cachedValue = root->db->getAttr(
parent->first->getAttrKey(), root->state.symbols);
assert(parent->first->cachedValue);
}
return {parent->first->cachedValue->first, parent->second};
}
Value & getValue()
{
if (!_value) {
@ -863,20 +906,24 @@ struct AttrCursor : std::enable_shared_from_this<AttrCursor>
{
if (root->db) {
if (!cachedValue)
cachedValue = root->db->getAttr(getAttrPath(), root->state.symbols);
cachedValue = root->db->getAttr(getAttrKey(), root->state.symbols);
if (cachedValue) {
if (auto attrs = std::get_if<std::vector<Symbol>>(&*cachedValue)) {
if (auto attrs = std::get_if<std::vector<Symbol>>(&cachedValue->second)) {
for (auto & attr : *attrs)
if (attr == name)
return std::make_shared<AttrCursor>(root, std::make_pair(shared_from_this(), name));
}
return nullptr;
return nullptr;
} else if (std::get_if<AttrDb::placeholder_t>(&cachedValue->second)) {
auto attr = root->db->getAttr({cachedValue->first, name}, root->state.symbols);
if (attr)
return std::make_shared<AttrCursor>(root, std::make_pair(shared_from_this(), name), nullptr, std::move(attr));
// Incomplete attrset, so need to fall thru and
// evaluate to see whether 'name' exists
} else
// FIXME: throw error?
return nullptr;
}
auto attr = root->db->getAttr(getAttrPath(name), root->state.symbols);
if (attr)
return std::make_shared<AttrCursor>(root, std::make_pair(shared_from_this(), name), nullptr, std::move(attr));
}
//printError("GET ATTR %s", getAttrPathStr(name));
@ -916,22 +963,20 @@ struct AttrCursor : std::enable_shared_from_this<AttrCursor>
{
if (root->db) {
if (!cachedValue)
cachedValue = root->db->getAttr(getAttrPath(), root->state.symbols);
if (cachedValue) {
if (auto s = std::get_if<std::string>(&*cachedValue)) {
cachedValue = root->db->getAttr(getAttrKey(), root->state.symbols);
if (cachedValue && !std::get_if<AttrDb::placeholder_t>(&cachedValue->second)) {
if (auto s = std::get_if<std::string>(&cachedValue->second)) {
//printError("GOT STRING %s", getAttrPathStr());
return *s;
} else
throw Error("unexpected type mismatch in evaluation cache");
throw Error("unexpected type mismatch in evaluation cache (string expected)");
}
}
//printError("GET STRING %s", getAttrPathStr());
auto s = root->state.forceString(getValue());
if (root->db) {
root->db->setAttr(getAttrPath(), s);
cachedValue = s;
}
if (root->db)
cachedValue = {root->db->setAttr(getAttrKey(), s), s};
return s;
}
@ -940,13 +985,13 @@ struct AttrCursor : std::enable_shared_from_this<AttrCursor>
{
if (root->db) {
if (!cachedValue)
cachedValue = root->db->getAttr(getAttrPath(), root->state.symbols);
if (cachedValue) {
if (auto attrs = std::get_if<std::vector<Symbol>>(&*cachedValue)) {
cachedValue = root->db->getAttr(getAttrKey(), root->state.symbols);
if (cachedValue && !std::get_if<AttrDb::placeholder_t>(&cachedValue->second)) {
if (auto attrs = std::get_if<std::vector<Symbol>>(&cachedValue->second)) {
//printError("GOT ATTRS %s", getAttrPathStr());
return *attrs;
} else
throw Error("unexpected type mismatch in evaluation cache");
throw Error("unexpected type mismatch in evaluation cache (attrs expected)");
}
}
@ -958,10 +1003,8 @@ struct AttrCursor : std::enable_shared_from_this<AttrCursor>
std::sort(attrs.begin(), attrs.end(), [](const Symbol & a, const Symbol & b) {
return (const string &) a < (const string &) b;
});
if (root->db) {
root->db->setAttr(getAttrPath(), attrs);
cachedValue = attrs;
}
if (root->db)
cachedValue = {root->db->setAttr(getAttrKey(), attrs), attrs};
return attrs;
}