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Add a test for RefScanSink and clean up the code

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Issue #5322.
This commit is contained in:
Eelco Dolstra 2021-10-04 14:29:42 +02:00
parent ef34fd0656
commit 77ebbc9f54
5 changed files with 105 additions and 30 deletions
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56
src/libstore/references.cc
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@ -11,11 +11,13 @@
namespace nix {
static unsigned int refLength = 32; /* characters */
static size_t refLength = 32; /* characters */
static void search(const unsigned char * s, size_t len,
StringSet & hashes, StringSet & seen)
static void search(
std::string_view s,
StringSet & hashes,
StringSet & seen)
{
static std::once_flag initialised;
static bool isBase32[256];
@ -25,7 +27,7 @@ static void search(const unsigned char * s, size_t len,
isBase32[(unsigned char) base32Chars[i]] = true;
});
for (size_t i = 0; i + refLength <= len; ) {
for (size_t i = 0; i + refLength <= s.size(); ) {
int j;
bool match = true;
for (j = refLength - 1; j >= 0; --j)
@ -35,7 +37,7 @@ static void search(const unsigned char * s, size_t len,
break;
}
if (!match) continue;
string ref((const char *) s + i, refLength);
std::string ref(s.substr(i, refLength));
if (hashes.erase(ref)) {
debug(format("found reference to '%1%' at offset '%2%'")
% ref % i);
@ -46,30 +48,23 @@ static void search(const unsigned char * s, size_t len,
}
struct RefScanSink : Sink
void RefScanSink::operator () (std::string_view data)
{
StringSet hashes;
StringSet seen;
/* It's possible that a reference spans the previous and current
fragment, so search in the concatenation of the tail of the
previous fragment and the start of the current fragment. */
auto s = tail;
s.append(data.data(), refLength);
search(s, hashes, seen);
string tail;
search(data, hashes, seen);
RefScanSink() { }
void operator () (std::string_view data) override
{
/* It's possible that a reference spans the previous and current
fragment, so search in the concatenation of the tail of the
previous fragment and the start of the current fragment. */
string s = tail + std::string(data, 0, refLength);
search((const unsigned char *) s.data(), s.size(), hashes, seen);
search((const unsigned char *) data.data(), data.size(), hashes, seen);
size_t tailLen = data.size() <= refLength ? data.size() : refLength;
tail = std::string(tail, tail.size() < refLength - tailLen ? 0 : tail.size() - (refLength - tailLen));
tail.append({data.data() + data.size() - tailLen, tailLen});
}
};
auto tailLen = std::min(data.size(), refLength);
auto rest = refLength - tailLen;
if (rest < tail.size())
tail = tail.substr(tail.size() - rest);
tail.append(data.data() + data.size() - tailLen, tailLen);
}
std::pair<StorePathSet, HashResult> scanForReferences(
@ -87,23 +82,24 @@ StorePathSet scanForReferences(
const Path & path,
const StorePathSet & refs)
{
RefScanSink refsSink;
TeeSink sink { refsSink, toTee };
StringSet hashes;
std::map<std::string, StorePath> backMap;
for (auto & i : refs) {
std::string hashPart(i.hashPart());
auto inserted = backMap.emplace(hashPart, i).second;
assert(inserted);
refsSink.hashes.insert(hashPart);
hashes.insert(hashPart);
}
/* Look for the hashes in the NAR dump of the path. */
RefScanSink refsSink(std::move(hashes));
TeeSink sink { refsSink, toTee };
dumpPath(path, sink);
/* Map the hashes found back to their store paths. */
StorePathSet found;
for (auto & i : refsSink.seen) {
for (auto & i : refsSink.getResult()) {
auto j = backMap.find(i);
assert(j != backMap.end());
found.insert(j->second);