Do not process messages while change number is happening.

app/src/main/java/org/thoughtcrime/securesms/jobmanager/impl/ChangeNumberConstraint.kt

@@ -0,0 +1,27 @@
+package org.thoughtcrime.securesms.jobmanager.impl
+
+import android.app.job.JobInfo
+import org.thoughtcrime.securesms.jobmanager.Constraint
+import org.thoughtcrime.securesms.keyvalue.SignalStore
+
+/**
+ * Constraint that, when added, means that a job cannot be performed while a change number operation is in progress.
+ */
+object ChangeNumberConstraint : Constraint {
+
+  const val KEY = "ChangeNumberConstraint"
+
+  override fun isMet(): Boolean {
+    return !SignalStore.misc().isChangeNumberLocked
+  }
+
+  override fun getFactoryKey(): String = KEY
+
+  override fun applyToJobInfo(jobInfoBuilder: JobInfo.Builder) = Unit
+
+  class Factory : Constraint.Factory<ChangeNumberConstraint> {
+    override fun create(): ChangeNumberConstraint {
+      return ChangeNumberConstraint
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/jobmanager/impl/ChangeNumberConstraintObserver.kt

@@ -0,0 +1,25 @@
+package org.thoughtcrime.securesms.jobmanager.impl
+
+import org.thoughtcrime.securesms.jobmanager.ConstraintObserver
+
+/**
+ * An observer for the [ChangeNumberConstraint]. This class expects to be told when a change happens,
+ * since the points at which it happens are triggered by application code.
+ */
+object ChangeNumberConstraintObserver : ConstraintObserver {
+
+  private const val REASON = "ChangeNumberConstraint"
+
+  private var notifier: ConstraintObserver.Notifier? = null
+
+  override fun register(notifier: ConstraintObserver.Notifier) {
+    this.notifier = notifier
+  }
+
+  /**
+   * Let the observer know that the change number state has changed.
+   */
+  fun onChange() {
+    notifier?.onConstraintMet(REASON)
+  }
+}