[receiver/sqlserver] Add new metric: lock wait count (#39930)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Adds a new metric `sqlserver.lock.wait.count` to represent the total
number of lock waits. This required adding a new metric to
`metadata.yaml`, updating the existing SQL Server perf counter query,
and updating tests.

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes #39892

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Updated tests for new metric, all are passing.

Also, tested to ensure the `instance_name` configuration option still
works (only metrics for the specified instance name are returned.) I
tested with it set to the right value and unset, returning the same
results (only one instance in my test environment,) and then also tested
with the wrong value and saw no metrics were returned. This has to be
done manually at this point as we don't have integration tests with a
real SQL Server instance. The existing tests rely on saved query data,
and aren't required to be updated with changes to the receiver.

<!--Describe the documentation added.-->
#### Documentation
Added note in `metadata.yaml` describing new metric.

Author: crobert-1

.chloggen/sqlserver_add_lock_wait_count.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receiver/sqlserver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add new metric `sqlserver.lock.wait.count`
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39892]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: This metric is disabled by default.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/sqlserverreceiver/documentation.md

@@ -359,6 +359,16 @@ Total number of lock timeouts.
 | ---- | ----------- | ---------- |
 | “{timeouts}/s” | Gauge | Double |
 
+### sqlserver.lock.wait.count
+
+Cumulative count of lock waits that occurred.
+
+This metric is only available when the receiver is configured to directly connect to SQL Server.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| {wait} | Sum | Int | Cumulative | true |
+
 ### sqlserver.login.rate
 
 Total number of logins.

receiver/sqlserverreceiver/factory.go

@@ -267,6 +267,7 @@ func isPerfCounterQueryEnabled(metrics *metadata.MetricsConfig) bool {
 		metrics.SqlserverDeadlockRate.Enabled ||
 		metrics.SqlserverIndexSearchRate.Enabled ||
 		metrics.SqlserverLockTimeoutRate.Enabled ||
+		metrics.SqlserverLockWaitCount.Enabled ||
 		metrics.SqlserverLockWaitRate.Enabled ||
 		metrics.SqlserverLoginRate.Enabled ||
 		metrics.SqlserverLogoutRate.Enabled ||

receiver/sqlserverreceiver/factory_test.go

@@ -264,7 +264,7 @@ func TestSetupQueries(t *testing.T) {
 
 	metricsMetadata, ok := metadata["metrics"].(map[string]any)
 	require.True(t, ok)
-	require.Len(t, metricsMetadata, 46,
+	require.Len(t, metricsMetadata, 47,
 		"Every time metrics are added or removed, the function `setupQueries` must "+
 			"be modified to properly account for the change. Please update `setupQueries` and then, "+
 			"and only then, update the expected metric count here.")

receiver/sqlserverreceiver/internal/metadata/generated_config.go

@@ -31,6 +31,8 @@ all_set:
       enabled: true
     sqlserver.lock.timeout.rate:
       enabled: true
+    sqlserver.lock.wait.count:
+      enabled: true
     sqlserver.lock.wait.rate:
       enabled: true
     sqlserver.lock.wait_time.avg:
@@ -136,6 +138,8 @@ none_set:
       enabled: false
     sqlserver.lock.timeout.rate:
       enabled: false
+    sqlserver.lock.wait.count:
+      enabled: false
     sqlserver.lock.wait.rate:
       enabled: false
     sqlserver.lock.wait_time.avg:

receiver/sqlserverreceiver/internal/metadata/generated_config_test.go

@@ -86,6 +86,15 @@ metrics:
     gauge:
       value_type: double
     extended_documentation: This metric is only available when running on Windows.
+  sqlserver.lock.wait.count:
+    enabled: false
+    description: Cumulative count of lock waits that occurred.
+    unit: "{wait}"
+    sum:
+      monotonic: true
+      aggregation_temporality: cumulative
+      value_type: int
+    extended_documentation: This metric is only available when the receiver is configured to directly connect to SQL Server.
   sqlserver.lock.wait.rate:
     enabled: true
     description: Number of lock requests resulting in a wait.