weaselab/conflict-set
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Move consumePartialKey, and allow empty partial key

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This commit is contained in:
Andrew Noyes
2024-08-12 16:18:58 -07:00
parent 567d385fbd
commit 142455dd28
1 changed files with 50 additions and 50 deletions
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100
ConflictSet.cpp
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@@ -1125,6 +1125,53 @@ Node *getFirstChildExists(Node *self) {
} }
} }
// Consume any partial key of `self`, and update `self` and
// `key` such that `self` is along the search path of `key`
void consumePartialKey(Node *&self, std::span<const uint8_t> &key,
InternalVersionT writeVersion, WriteContext *tls) {
if (self->partialKeyLen == 0) {
return;
}
// 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;
// Since root cannot have a partial key
assert(old->parent != nullptr);
InternalVersionT oldMaxVersion = exchangeMaxVersion(old, writeVersion);
// *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);
}
// Caller is responsible for assigning a non-null pointer to the returned // Caller is responsible for assigning a non-null pointer to the returned
// reference if null. Updates child's max version to `newMaxVersion` if child // reference if null. Updates child's max version to `newMaxVersion` if child
// exists but does not have a partial key. // exists but does not have a partial key.
@@ -2743,51 +2790,6 @@ checkMaxBetweenExclusiveImpl<true>(Node *n, int begin, int end,
InternalVersionT readVersion, ReadContext *); InternalVersionT readVersion, ReadContext *);
#endif #endif
// Consume the partial key of `self` (which must exist), and update `self` and
// `key` such that `self` is along the search path of `key`
void consumePartialKey(Node *&self, std::span<const uint8_t> &key,
InternalVersionT writeVersion, WriteContext *tls) {
assert(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;
// Since root cannot have a partial key
assert(old->parent != nullptr);
InternalVersionT oldMaxVersion = exchangeMaxVersion(old, writeVersion);
// *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 the pointer to the newly inserted node in the tree. Caller // Returns a pointer the pointer to the newly inserted node in the tree. Caller
// must set `entryPresent`, and `entry` fields. All nodes along the search path // must set `entryPresent`, and `entry` fields. All nodes along the search path
// of the result will have `maxVersion` set to `writeVersion` as a // of the result will have `maxVersion` set to `writeVersion` as a
@@ -2814,11 +2816,9 @@ Node **insert(Node **self, std::span<const uint8_t> key,
self = &child; self = &child;
if ((*self)->partialKeyLen > 0) { consumePartialKey(*self, key, writeVersion, tls);
consumePartialKey(*self, key, writeVersion, tls); assert(maxVersion(*self, impl) <= writeVersion);
assert(maxVersion(*self, impl) <= writeVersion); setMaxVersion(*self, impl, writeVersion);
setMaxVersion(*self, impl, writeVersion);
}
} }
} }