[Cost Report] Add some UI fixes

sky/cli.py

@@ -1694,24 +1694,42 @@ def cost_report(all: bool):  # pylint: disable=redefined-builtin
       - clusters that were terminated/stopped on the cloud console.
     """
     cluster_records = core.cost_report()
+
     nonreserved_cluster_records = []
     reserved_clusters = dict()
     for cluster_record in cluster_records:
         cluster_name = cluster_record['name']
         if cluster_name in backend_utils.SKY_RESERVED_CLUSTER_NAMES:
             cluster_group_name = backend_utils.SKY_RESERVED_CLUSTER_NAMES[
                 cluster_name]
-            reserved_clusters[cluster_group_name] = cluster_record
+            # to display most recent entry for each reserved cluster
+            if cluster_group_name not in reserved_clusters:
+                reserved_clusters[cluster_group_name] = cluster_record
         else:
             nonreserved_cluster_records.append(cluster_record)
 
-    status_utils.show_cost_report_table(nonreserved_cluster_records, all)
+    total_cost = status_utils.get_total_cost_of_displayed_records(
+        nonreserved_cluster_records, all)
 
+    status_utils.show_cost_report_table(nonreserved_cluster_records, all)
     for cluster_group_name, cluster_record in reserved_clusters.items():
         status_utils.show_cost_report_table(
             [cluster_record], all, reserved_group_name=cluster_group_name)
+        total_cost += cluster_record['total_cost']
+
+    click.echo(f'\n{colorama.Style.BRIGHT}'
+               f'Total Cost: ${total_cost:.2f}{colorama.Style.RESET_ALL}')
+
+    if not all:
+        click.secho(
+            f'Showing the {status_utils.NUM_COST_REPORT_LINES} '
+            'most recent clusters. '
+            'To see all clusters in history, '
+            'pass the --all flag.',
+            fg='yellow')
+
     click.secho(
-        'NOTE: This feature is experimental. '
+        'This feature is experimental. '
         'Costs for clusters with auto{stop,down} '
         'scheduled may not be accurate.',
         fg='yellow')

sky/global_user_state.py

@@ -459,6 +459,8 @@ def _get_cluster_duration(cluster_hash: str) -> int:
 
     for i, (start_time, end_time) in enumerate(usage_intervals):
         # duration from latest start time to time of query
+        if start_time is None:
+            continue
         if end_time is None:
             assert i == len(usage_intervals) - 1, i
             end_time = int(time.time())

sky/utils/cli_utils/status_utils.py

@@ -11,6 +11,7 @@
 from sky.utils import log_utils
 
 _COMMAND_TRUNC_LENGTH = 25
+NUM_COST_REPORT_LINES = 5
 
 # A record in global_user_state's 'clusters' table.
 _ClusterRecord = Dict[str, Any]
@@ -104,6 +105,20 @@ def show_status_table(cluster_records: List[_ClusterRecord],
     return num_pending_autostop
 
 
+def get_total_cost_of_displayed_records(
+        cluster_records: List[_ClusterCostReportRecord], display_all: bool):
+    """Compute total cost of records to be displayed in cost report."""
+    cluster_records.sort(
+        key=lambda report: -_get_status_value_for_cost_report(report))
+
+    displayed_records = cluster_records[:NUM_COST_REPORT_LINES]
+    if display_all:
+        displayed_records = cluster_records
+
+    total_cost = sum(record['total_cost'] for record in displayed_records)
+    return total_cost
+
+
 def show_cost_report_table(cluster_records: List[_ClusterCostReportRecord],
                            show_all: bool,
                            reserved_group_name: Optional[str] = None):
@@ -153,7 +168,15 @@ def show_cost_report_table(cluster_records: List[_ClusterCostReportRecord],
             columns.append(status_column.name)
     cluster_table = log_utils.create_table(columns)
 
-    for record in cluster_records:
+    num_lines_to_display = NUM_COST_REPORT_LINES
+    if show_all:
+        num_lines_to_display = len(cluster_records)
+
+    # prioritize showing non-terminated clusters in table
+    cluster_records.sort(
+        key=lambda report: -_get_status_value_for_cost_report(report))
+
+    for record in cluster_records[:num_lines_to_display]:
         row = []
         for status_column in status_columns:
             if status_column.show_by_default or show_all:
@@ -340,6 +363,14 @@ def _is_pending_autostop(cluster_record: _ClusterRecord) -> bool:
 # ---- 'sky cost-report' helper functions below ----
 
 
+def _get_status_value_for_cost_report(
+        cluster_cost_report_record: _ClusterCostReportRecord) -> int:
+    status = cluster_cost_report_record['status']
+    if status is None:
+        return -1
+    return 1
+
+
 def _get_status_for_cost_report(
         cluster_cost_report_record: _ClusterCostReportRecord) -> str:
     status = cluster_cost_report_record['status']