kv: make kv.transaction.write_buffering.max_buffer_size bytes setting

This was incorrectly called an int setting previously. While here,
handle the zero case correctly too.

Epic: none

Release note: None

Author: arulajmani

docs/generated/settings/settings-for-tenants.txt

@@ -99,7 +99,7 @@ kv.transaction.max_refresh_spans_bytes	integer	4194304	maximum number of bytes u
 kv.transaction.randomized_anchor_key.enabled	boolean	false	dictates whether a transactions anchor key is randomized or not	application
 kv.transaction.reject_over_max_intents_budget.enabled	boolean	false	if set, transactions that exceed their lock tracking budget (kv.transaction.max_intents_bytes) are rejected instead of having their lock spans imprecisely compressed	application
 kv.transaction.write_buffering.enabled	boolean	false	if enabled, transactional writes are buffered on the client	application
-kv.transaction.write_buffering.max_buffer_size	integer	4194304	if non-zero, defines that maximum size of the buffer that will be used to buffer transactional writes per-transaction	application
+kv.transaction.write_buffering.max_buffer_size	byte size	4.0 MiB	if non-zero, defines that maximum size of the buffer that will be used to buffer transactional writes per-transaction	application
 kv.transaction.write_pipelining.locking_reads.enabled	boolean	true	if enabled, transactional locking reads are pipelined through Raft consensus	application
 kv.transaction.write_pipelining.ranged_writes.enabled	boolean	true	if enabled, transactional ranged writes are pipelined through Raft consensus	application
 kv.transaction.write_pipelining.enabled (alias: kv.transaction.write_pipelining_enabled)	boolean	true	if enabled, transactional writes are pipelined through Raft consensus	application

docs/generated/settings/settings.html

@@ -128,7 +128,7 @@
 <tr><td><div id="setting-kv-transaction-randomized-anchor-key-enabled" class="anchored"><code>kv.transaction.randomized_anchor_key.enabled</code></div></td><td>boolean</td><td><code>false</code></td><td>dictates whether a transactions anchor key is randomized or not</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-kv-transaction-reject-over-max-intents-budget-enabled" class="anchored"><code>kv.transaction.reject_over_max_intents_budget.enabled</code></div></td><td>boolean</td><td><code>false</code></td><td>if set, transactions that exceed their lock tracking budget (kv.transaction.max_intents_bytes) are rejected instead of having their lock spans imprecisely compressed</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-kv-transaction-write-buffering-enabled" class="anchored"><code>kv.transaction.write_buffering.enabled</code></div></td><td>boolean</td><td><code>false</code></td><td>if enabled, transactional writes are buffered on the client</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
-<tr><td><div id="setting-kv-transaction-write-buffering-max-buffer-size" class="anchored"><code>kv.transaction.write_buffering.max_buffer_size</code></div></td><td>integer</td><td><code>4194304</code></td><td>if non-zero, defines that maximum size of the buffer that will be used to buffer transactional writes per-transaction</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
+<tr><td><div id="setting-kv-transaction-write-buffering-max-buffer-size" class="anchored"><code>kv.transaction.write_buffering.max_buffer_size</code></div></td><td>byte size</td><td><code>4.0 MiB</code></td><td>if non-zero, defines that maximum size of the buffer that will be used to buffer transactional writes per-transaction</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-kv-transaction-write-pipelining-locking-reads-enabled" class="anchored"><code>kv.transaction.write_pipelining.locking_reads.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>if enabled, transactional locking reads are pipelined through Raft consensus</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-kv-transaction-write-pipelining-ranged-writes-enabled" class="anchored"><code>kv.transaction.write_pipelining.ranged_writes.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>if enabled, transactional ranged writes are pipelined through Raft consensus</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-kv-transaction-write-pipelining-enabled" class="anchored"><code>kv.transaction.write_pipelining.enabled<br />(alias: kv.transaction.write_pipelining_enabled)</code></div></td><td>boolean</td><td><code>true</code></td><td>if enabled, transactional writes are pipelined through Raft consensus</td><td>Serverless/Dedicated/Self-Hosted</td></tr>

pkg/kv/kvclient/kvcoord/txn_interceptor_write_buffer.go

@@ -35,7 +35,7 @@ var BufferedWritesEnabled = settings.RegisterBoolSetting(
 	settings.WithPublic,
 )
 
-var bufferedWritesMaxBufferSize = settings.RegisterIntSetting(
+var bufferedWritesMaxBufferSize = settings.RegisterByteSizeSetting(
 	settings.ApplicationLevel,
 	"kv.transaction.write_buffering.max_buffer_size",
 	"if non-zero, defines that maximum size of the "+
@@ -246,7 +246,9 @@ func (twb *txnWriteBuffer) SendLocked(
 	// and flush the buffer.
 	maxSize := bufferedWritesMaxBufferSize.Get(&twb.st.SV)
 	bufSize := twb.estimateSize(ba) + twb.bufferSize
-	if bufSize > maxSize {
+	// NB: if bufferedWritesMaxBufferSize is set to 0 then we effectively disable
+	// any buffer limiting.
+	if maxSize != 0 && bufSize > maxSize {
 		// TODO(arul): add some metrics for this case.
 		log.VEventf(ctx, 2, "flushing buffer because buffer size (%s) exceeds max size (%s)",
 			humanizeutil.IBytes(bufSize),