weaselab/conflict-set
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Extract consumePartialKey to its own function

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This commit is contained in:
Andrew Noyes
2024-08-06 13:20:44 -07:00
parent ed5589e4ed
commit 051eb5919d
1 changed files with 52 additions and 43 deletions
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95
ConflictSet.cpp
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@@ -2883,56 +2883,65 @@ checkMaxBetweenExclusiveImpl<true>(Node *n, int begin, int end,
InternalVersionT readVersion, ReadContext *); InternalVersionT readVersion, ReadContext *);
#endif #endif
// Consume the partial key of `self` if it exists, and update `self` and `key`
// such that `self` is along the search path of `key`, and has maxVersion
// `writeVersion`
void consumePartialKey(Node *&self, std::span<const uint8_t> &key,
InternalVersionT writeVersion, WriteContext *tls,
ConflictSet::Impl *impl) {
if (self->partialKeyLen > 0) {
// Handle an existing partial key
int commonLen = std::min<int>(self->partialKeyLen, key.size());
int partialKeyIndex =
longestCommonPrefix(self->partialKey(), key.data(), commonLen);
if (partialKeyIndex < self->partialKeyLen) {
auto *old = self;
InternalVersionT oldMaxVersion =
exchangeMaxVersion(old, writeVersion, impl);
// *self will have one child (old)
auto *newSelf = tls->allocate<Node3>(partialKeyIndex);
newSelf->parent = old->parent;
newSelf->parentsIndex = old->parentsIndex;
newSelf->partialKeyLen = partialKeyIndex;
newSelf->entryPresent = false;
newSelf->numChildren = 1;
memcpy(newSelf->partialKey(), old->partialKey(), newSelf->partialKeyLen);
uint8_t oldDistinguishingByte = old->partialKey()[partialKeyIndex];
old->parent = newSelf;
old->parentsIndex = oldDistinguishingByte;
newSelf->index[0] = oldDistinguishingByte;
newSelf->children[0] = old;
newSelf->childMaxVersion[0] = oldMaxVersion;
self = newSelf;
memmove(old->partialKey(), old->partialKey() + partialKeyIndex + 1,
old->partialKeyLen - (partialKeyIndex + 1));
old->partialKeyLen -= partialKeyIndex + 1;
// We would consider decreasing capacity here, but we can't invalidate
// old since it's not on the search path. setOldestVersion will clean it
// up.
}
key = key.subspan(partialKeyIndex, key.size() - partialKeyIndex);
}
}
// Returns a pointer to the newly inserted node. Caller must set // Returns a pointer to the newly inserted node. Caller must set
// `entryPresent`, and `entry` fields. All nodes along the search path of the // `entryPresent`, and `entry` fields. All nodes along the search path of the
// result will have `maxVersion` set to `writeVersion` as a postcondition. Nodes // result will have `maxVersion` set to `writeVersion` as a postcondition. Nodes
// along the search path may be invalidated. // along the search path may be invalidated.
[[nodiscard]] Node *insert(Node **self, std::span<const uint8_t> key, [[nodiscard]]
InternalVersionT writeVersion, WriteContext *tls, Node *insert(Node **self, std::span<const uint8_t> key,
ConflictSet::Impl *impl) { InternalVersionT writeVersion, WriteContext *tls,
ConflictSet::Impl *impl) {
for (;; ++tls->accum.insert_iterations) { for (;; ++tls->accum.insert_iterations) {
if ((*self)->partialKeyLen > 0) { consumePartialKey(*self, key, writeVersion, tls, impl);
// Handle an existing partial key
int commonLen = std::min<int>((*self)->partialKeyLen, key.size());
int partialKeyIndex =
longestCommonPrefix((*self)->partialKey(), key.data(), commonLen);
if (partialKeyIndex < (*self)->partialKeyLen) {
auto *old = *self;
InternalVersionT oldMaxVersion =
exchangeMaxVersion(old, writeVersion, impl);
// *self will have one child (old)
auto *newSelf = tls->allocate<Node3>(partialKeyIndex);
newSelf->parent = old->parent;
newSelf->parentsIndex = old->parentsIndex;
newSelf->partialKeyLen = partialKeyIndex;
newSelf->entryPresent = false;
newSelf->numChildren = 1;
memcpy(newSelf->partialKey(), old->partialKey(),
newSelf->partialKeyLen);
uint8_t oldDistinguishingByte = old->partialKey()[partialKeyIndex];
old->parent = newSelf;
old->parentsIndex = oldDistinguishingByte;
newSelf->index[0] = oldDistinguishingByte;
newSelf->children[0] = old;
newSelf->childMaxVersion[0] = oldMaxVersion;
*self = newSelf;
memmove(old->partialKey(), old->partialKey() + partialKeyIndex + 1,
old->partialKeyLen - (partialKeyIndex + 1));
old->partialKeyLen -= partialKeyIndex + 1;
// We would consider decreasing capacity here, but we can't invalidate
// old since it's not on the search path. setOldestVersion will clean it
// up.
}
key = key.subspan(partialKeyIndex, key.size() - partialKeyIndex);
}
assert(maxVersion(*self, impl) <= writeVersion); assert(maxVersion(*self, impl) <= writeVersion);
setMaxVersion(*self, impl, writeVersion); setMaxVersion(*self, impl, writeVersion);