go/roothash: Drop support for multiple committees

.changelog/3179.breaking.md

@@ -1,10 +1,8 @@
-go/worker/compute/merge: Drop support for multiple committees
+go/roothash: Drop support for multiple committees
 
 Since there is currently no transaction scheduler implementation which would
-support multiple committees, there is no sense in the merge node to try to
-support such cases as it could be a source of bugs. Additionally it results
-in extra round trips to storage nodes due to the Merge operation which in
-case of a single committee does not do anything.
+support multiple committees, there is no sense in having the merge node as it
+could be a source of bugs.
 
 The merge node is also the only client for the Merge* storage operations, so
 they can just be removed in order to reduce the exposed API surface.

docs/index.md

@@ -60,7 +60,6 @@ implementations.
   * Transaction Processing Pipeline
     * Transaction Scheduler Nodes
     * Executor Nodes
-    * Merge Nodes
     * Storage Nodes
     * Key Manager Nodes
 * Oasis Node (`oasis-node`)

docs/oasis-node/metrics.md

@@ -76,7 +76,6 @@ oasis_storage_successes | Counter | Number of storage successes. | call | [stora
 oasis_storage_value_size | Summary | Storage call value size (bytes). | call | [storage](../../go/storage/metrics.go)
 oasis_up | Gauge | Is oasis-test-runner active for specific scenario. |  | [oasis-node/cmd/common/metrics](../../go/oasis-node/cmd/common/metrics/metrics.go)
 oasis_worker_aborted_batch_count | Counter | Number of aborted batches. | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
-oasis_worker_aborted_merge_count | Counter | Number of aborted merges. | runtime | [worker/compute/merge/committee](../../go/worker/compute/merge/committee/node.go)
 oasis_worker_batch_processing_time | Summary | Time it takes for a batch to finalize (seconds). | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
 oasis_worker_batch_read_time | Summary | Time it takes to read a batch from storage (seconds). | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
 oasis_worker_batch_runtime_processing_time | Summary | Time it takes for a batch to be processed by the runtime (seconds). | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
@@ -85,12 +84,9 @@ oasis_worker_epoch_number | Gauge | Current epoch number as seen by the worker.
 oasis_worker_epoch_transition_count | Counter | Number of epoch transitions. | runtime | [worker/common/committee](../../go/worker/common/committee/node.go)
 oasis_worker_execution_discrepancy_detected_count | Counter | Number of detected execute discrepancies. | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
 oasis_worker_failed_round_count | Counter | Number of failed roothash rounds. | runtime | [worker/common/committee](../../go/worker/common/committee/node.go)
-oasis_worker_inconsistent_merge_root_count | Counter | Number of inconsistent merge roots. | runtime | [worker/compute/merge/committee](../../go/worker/compute/merge/committee/node.go)
-oasis_worker_merge_discrepancy_detected_count | Counter | Number of detected merge discrepancies. | runtime | [worker/compute/merge/committee](../../go/worker/compute/merge/committee/node.go)
 oasis_worker_node_registered | Gauge | Is oasis node registered (binary). |  | [worker/registration](../../go/worker/registration/worker.go)
 oasis_worker_processed_block_count | Counter | Number of processed roothash blocks. | runtime | [worker/common/committee](../../go/worker/common/committee/node.go)
 oasis_worker_processed_event_count | Counter | Number of processed roothash events. | runtime | [worker/common/committee](../../go/worker/common/committee/node.go)
-oasis_worker_roothash_merge_commit_latency | Summary | Latency of roothash merge commit (seconds). | runtime | [worker/compute/merge/committee](../../go/worker/compute/merge/committee/node.go)
 oasis_worker_storage_commit_latency | Summary | Latency of storage commit calls (state + outputs) (seconds). | runtime | [worker/compute/executor/committee](../../go/worker/compute/executor/committee/node.go)
 oasis_worker_storage_full_round | Gauge | The last round that was fully synced and finalized. | runtime | [worker/storage/committee](../../go/worker/storage/committee/node.go)
 oasis_worker_storage_pending_round | Gauge | The last round that is in-flight for syncing. | runtime | [worker/storage/committee](../../go/worker/storage/committee/node.go)

docs/runtime/index.md

@@ -128,7 +128,6 @@ roles (it can have multiple roles at once):
 
 * Transaction scheduler.
 * Executor node (primary or backup).
-* Merge node (primary or backup).
 
 Subject to runtime configuration, each committee can contain multiple nodes of
 the same kind (e.g., multiple executor nodes). Some are considered _primary_

docs/toc.md

@@ -30,7 +30,7 @@
     * [Operation Model](runtime/index.md#operation-model)
     * [Runtime Host Protocol](runtime/runtime-host-protocol.md)
     * [Identifiers](runtime/identifiers.md)
-* Oasis Node (`oasis-node`)
+* Oasis Node
   * [RPC](oasis-node/rpc.md)
   * [Metrics](oasis-node/metrics.md)
 

go/consensus/tendermint/apps/roothash/api.go

@@ -68,24 +68,12 @@ type ValueExecutorCommitted struct {
 	Event roothash.ExecutorCommittedEvent `json:"event"`
 }
 
-// ValueMergeCommitted is the value component of a KeyMergeCommitted.
-type ValueMergeCommitted struct {
-	ID    common.Namespace             `json:"id"`
-	Event roothash.MergeCommittedEvent `json:"event"`
-}
-
 // ValueFinalized is the value component of a TagFinalized.
 type ValueFinalized struct {
 	ID    common.Namespace `json:"id"`
 	Round uint64           `json:"round"`
 }
 
-// ValueMergeDiscrepancyDetected is the value component of a KeyMergeDiscrepancyDetected.
-type ValueMergeDiscrepancyDetected struct {
-	Event roothash.MergeDiscrepancyDetectedEvent `json:"event"`
-	ID    common.Namespace                       `json:"id"`
-}
-
 // ValueExecutionDiscrepancyDetected is the value component of a KeyMergeDiscrepancyDetected.
 type ValueExecutionDiscrepancyDetected struct {
 	ID    common.Namespace                           `json:"id"`