weaselab/versioned-map
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Change entry representation to reduce number of entries

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This commit is contained in:
Andrew Noyes
2024-05-01 12:40:26 -07:00
parent 0e0c225c52
commit a14f208c39
2 changed files with 21 additions and 16 deletions
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35
VersionedMap.cpp
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@@ -50,16 +50,21 @@ namespace weaselab {
struct Entry { struct Entry {
int64_t insertVersion; int64_t insertVersion;
int param1Len; int keyLen;
int param2Len; // Negative if this key is cleared
int valLen;
mutable int refCount; mutable int refCount;
uint32_t priority; uint32_t priority;
VersionedMap::MutationType mutationType; // True if mutations in (pred, this) are cleared. If false, (pred, this)
// should be read through to the underlying data structure.
bool clearTo;
const uint8_t *getParam1() const { return (const uint8_t *)(this + 1); } // There's an extra zero byte past the end of getKey, used for
// reconstructing logical mutations without copies.
const uint8_t *getKey() const { return (const uint8_t *)(this + 1); }
const uint8_t *getParam2() const { const uint8_t *getVal() const {
return (const uint8_t *)(this + 1) + param1Len; return (const uint8_t *)(this + 1) + 1 + keyLen;
} }
void addref() const { ++refCount; } void addref() const { ++refCount; }
@@ -70,18 +75,18 @@ struct Entry {
} }
} }
static Entry *make(int64_t insertVersion, const uint8_t *param1, static Entry *make(int64_t insertVersion, const uint8_t *key, int keyLen,
int param1Len, const uint8_t *param2, int param2Len, const uint8_t *val, int valLen, bool clearTo) {
VersionedMap::MutationType mutationType) { auto e = (Entry *)malloc(sizeof(Entry) + keyLen + 1 + std::max(valLen, 0));
auto e = (Entry *)malloc(sizeof(Entry) + param1Len + param2Len);
e->insertVersion = insertVersion; e->insertVersion = insertVersion;
e->param1Len = param1Len; e->keyLen = keyLen;
e->param2Len = param2Len; e->valLen = valLen;
e->refCount = 1; e->refCount = 1;
e->priority = rand(); // TODO e->priority = rand(); // TODO
e->mutationType = mutationType; e->clearTo = clearTo;
memcpy((uint8_t *)e->getParam1(), param1, param1Len); memcpy((uint8_t *)e->getKey(), key, keyLen);
memcpy((uint8_t *)e->getParam2(), param2, param2Len); ((uint8_t *)e->getKey())[keyLen] = 0;
memcpy((uint8_t *)e->getVal(), val, std::max(valLen, 0));
return e; return e;
} }
}; };

2
include/VersionedMap.h
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@@ -141,7 +141,7 @@ struct VersionedMap {
/** Map starts with no mutations, with `getOldestVersion()` == `getVersion()` /** Map starts with no mutations, with `getOldestVersion()` == `getVersion()`
* == `version`. */ * == `version`. */
VersionedMap(int64_t version); explicit VersionedMap(int64_t version);
~VersionedMap(); ~VersionedMap();