hyperfiddle.electric.impl.mount-point — com.hyperfiddle/electric v3-alpha-4-g9948fc0b

A mount-point instance maintains :

• a hash map storing items indexed by tag. An item is a mutable object tracking the lifecycle of each entry in the resulting incseq.
• a set of active readers. Each mutation of the store sends an invalidation event for the item being touched to the readers currently active.

A reader process maintains :

• a call tree isomorphic to the subset of the application's call tree restricted to the ancestors of active items. Leaves are items, nodes are either blocks or calls, block children are items or calls, call children are blocks, the root is a call.
• a hash map storing blocks indexed by frame. A block is a mutable object tracking each known frame. A frame is known when either it's an ancestor of an active item, or it's currently being mounted by a call that is in the common ancestry of an active item.
• a mailbox for step events on calls and another one for invalidation events on items. Both mailboxes are consumed during reader process transfer, call events take priority over the item events but ordering of events within a single mailbox is irrelevant. The processing of each event mutates the call tree and generates a diff, then the concatenation of successive diffs is returned. When the reader is spawned, an invalidation event is posted for each active item.

On item invalidation event :

• If the item is inactive :
  • If it was attached in the call tree, it is detached from the tree and a shrink is generated if the item was mounted.
  • If it was detached from the call tree, nothing happens.
• If the item is active :
  • If it was attached in the call tree, a change is generated if the item was mounted.
  • If it was detached from the call tree, it is attached to the tree and a grow is generated if the item was mounted.

On call step event :

1. Apply permutation. The call permutation must be expanded to take into account the offset and length of the call segment in the current sequence state.
2. Apply changes. For each item change that is not a grow, the block associated to previous frame is unmounted. The new frame is then associated to its block and mounted.
3. Apply shrinks. The blocks associated with removed frames are unmounted.

Unmounting a block generates a shrink for each active item having this block's frame as an ancestor. Mounting a block generates a grow for each active item having this block's frame as an ancestor.

apply-change clj

(apply-change call change diff)

apply-permutation clj

(apply-permutation call permutation diff)

apply-shrink clj

(apply-shrink call degree shrink diff)

block-attach-to-call clj

(block-attach-to-call block)

block-attach-to-tree clj

(block-attach-to-tree block reader diff)

block-child clj

(block-child block id)

block-empty? clj

(block-empty? block)

block-index clj

(block-index call id)

block-mount clj

(block-mount block offset diff)

block-release clj

(block-release block)

block-set-child clj

(block-set-child block id child)

block-single-child clj

(block-single-child block)

block-slot-children clj

block-slot-frame clj

block-slot-index clj

block-slot-next clj

block-slot-parent clj

block-slot-prev clj

block-slot-weights clj

block-slots clj

block-unmount clj

(block-unmount block diff)

block-weight clj

(block-weight block)

call-attach-to-block clj

(call-attach-to-block call block)

call-cancel clj

(call-cancel call)

call-discard clj

(call-discard call)

call-index clj

(call-index block id)

call-make-ancestors clj

(call-make-ancestors call)

call-release clj

(call-release call)

call-slot clj

(call-slot call)

call-slot-buffer clj

call-slot-children clj

call-slot-parent clj

call-slot-process clj

call-slot-queue clj

call-slot-reader clj

call-slot-weight clj

call-slots clj

call-spawn clj

(call-spawn call)

call-transfer clj

(call-transfer call diff)

call-update-weights clj

(call-update-weights call delta)

call-weight clj

(call-weight call)

change clj

(change item diff)

create clj

(create peer)

current-size clj

(current-size reader)

detach-root clj

(detach-root block id)

enqueue-call clj

(enqueue-call reader call)

enqueue-item clj

(enqueue-item reader item)

ensure-capacity clj

(ensure-capacity buffer cap)

enter clj

(enter state)

error clj

(error msg)

exit clj

(exit state held)

get-block clj

(get-block reader frame)

item-attach-to-block clj

(item-attach-to-block item block id diff)

item-attach-to-tree clj

(item-attach-to-tree item reader diff)

item-cancel clj

(item-cancel item)

item-detach-from-tree clj

(item-detach-from-tree item diff)

item-slot-parent clj

item-slot-queue clj

item-slot-state clj

item-slot-tag clj

item-slots clj

local-block-offset clj

(local-block-offset call index)

local-call-index clj

(local-call-index block index)

make-block clj

(make-block reader frame)

make-call clj

(make-call reader child)

reader-cancel clj

(reader-cancel reader)

reader-event clj

(reader-event reader)

reader-pending clj

(reader-pending reader)

reader-slot-alive clj

reader-slot-blocks clj

reader-slot-call-queue clj

reader-slot-done clj

reader-slot-item-queue clj

reader-slot-pending clj

reader-slot-root clj

reader-slot-state clj

reader-slot-step clj

reader-slots clj

reader-spawn clj

(reader-spawn state step done)

reader-transfer clj

(reader-transfer reader)

root-down clj

(root-down call)

root-up clj

(root-up call diff)

slot-items clj

slot-lock clj

slot-peer clj

slot-pending clj

slot-reader clj

slots clj

swap-indices clj

(swap-indices call i j)

terminate clj

(terminate reader)

unlock clj

(unlock state held)

update-local-weights clj

(update-local-weights weights id delta)

update-weights clj

(update-weights block id delta)