From 4c3a537ab998d02d33f4335aae0e5da89da22d5e Mon Sep 17 00:00:00 2001
From: Praveen K V <kvpraveen@juniper.net>
Date: Sat, 7 Mar 2015 13:30:07 +0530
Subject: [PATCH] Invoke RetryDelete() on unregister of last listener

The lifetime actors for route db-tables will wait till number of entries
in dbtable is 0 and there are no listeners to the table.

DBTable infrastructure invokes RetryDelete() when a DBTablePartition
becomes empty. In addition, it should invoke RetryDelete() when all
db-table listeners are gone also.

The fix will invoke RetryDelete() when number of listeners becomes empty

Change-Id: I659a07bde0b790be08b5cafe1349c3c6b640d1ec
Closes-Bug: #1429348
---
 src/db/db_table.cc          |  4 ++++
 src/db/db_table.h           |  6 +++---
 src/db/test/db_base_test.cc |  6 ++++++
 src/db/test/db_test.cc      | 12 ++++++++++--
 src/db/test/db_test_cmn.h   | 10 ++++++++++
 5 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/db/db_table.cc b/src/db/db_table.cc
index e110477ac20..0c9bb9782b1 100644
--- a/src/db/db_table.cc
+++ b/src/db/db_table.cc
@@ -114,6 +114,10 @@ DBTableBase::ListenerId DBTableBase::Register(ChangeCallback callback) {
 
 void DBTableBase::Unregister(ListenerId listener) {
     info_->Unregister(listener);
+    // If a table is marked for deletion, then we may trigger the deletion
+    // process when the last client is removed
+    if (info_->empty())
+        RetryDelete();
 }
 
 bool DBTableBase::Enqueue(DBRequest *req) {
diff --git a/src/db/db_table.h b/src/db/db_table.h
index 8905699bbae..6a42d851bd7 100644
--- a/src/db/db_table.h
+++ b/src/db/db_table.h
@@ -81,6 +81,9 @@ class DBTableBase {
     // Calculate the size across all partitions.
     virtual size_t Size() const { return 0; }
 
+    // Suspended deletion resume hook for user function
+    virtual void RetryDelete() { }
+
     DB *database() { return db_; }
     const DB *database() const { return db_; }
 
@@ -143,9 +146,6 @@ class DBTable : public DBTableBase {
     // Delete hook for user function
     virtual bool Delete(DBEntry *entry, const DBRequest *req);
 
-    // Suspended deletion resume hook for user function
-    virtual void RetryDelete() { }
-
     void WalkCompleteCallback(DBTableBase *tbl_base);
     void NotifyAllEntries();
 
diff --git a/src/db/test/db_base_test.cc b/src/db/test/db_base_test.cc
index c2f749d72b6..9089b1a7501 100644
--- a/src/db/test/db_base_test.cc
+++ b/src/db/test/db_base_test.cc
@@ -223,7 +223,13 @@ class VlanTable : public DBTableBase {
         return table;
     }
 
+    void RetryDelete() {
+        retry_delete_count_++;
+    }
+
+    uint32_t retry_delete_count() const { return retry_delete_count_; }
 private:
+    uint32_t retry_delete_count_;
     std::vector<VlanTablePart *> partitions_;
     DISALLOW_COPY_AND_ASSIGN(VlanTable);
 };
diff --git a/src/db/test/db_test.cc b/src/db/test/db_test.cc
index 07cc377b48d..a85ec1476b8 100644
--- a/src/db/test/db_test.cc
+++ b/src/db/test/db_test.cc
@@ -79,8 +79,10 @@ class Vlan : public DBEntry {
 
 class VlanTable : public DBTable {
 public:
-    VlanTable(DB *db) : DBTable(db, "__vlan__.0") { };
-    ~VlanTable() { };
+    VlanTable(DB *db) :
+        DBTable(db, "__vlan__.0"), retry_delete_count_(0), del_req_count_(0) {
+    }
+    ~VlanTable() { }
 
     uint32_t del_req_count() const { return del_req_count_; }
 
@@ -136,6 +138,12 @@ class VlanTable : public DBTable {
         return table;
     }
 
+    void RetryDelete() {
+        retry_delete_count_++;
+    }
+
+    uint32_t retry_delete_count() const { return retry_delete_count_; }
+    uint32_t retry_delete_count_;
     uint32_t del_req_count_;
     DISALLOW_COPY_AND_ASSIGN(VlanTable);
 };
diff --git a/src/db/test/db_test_cmn.h b/src/db/test/db_test_cmn.h
index 1e975e701f7..89c46dcda95 100644
--- a/src/db/test/db_test_cmn.h
+++ b/src/db/test/db_test_cmn.h
@@ -151,12 +151,15 @@ class DBTest : public ::testing::Test {
 
 TEST_F(DBTest, Basic) {
     EXPECT_EQ(itbl, db_.FindTable("db.test.vlan.0"));
+    uint32_t retry_delete_count = itbl->retry_delete_count();
 
     tid_ = 
         itbl->Register(boost::bind(&DBTest::DBTestListener, this, _1, _2));
     EXPECT_EQ(tid_, 0);
 
     itbl->Unregister(tid_);
+    EXPECT_EQ(itbl->retry_delete_count(), retry_delete_count+1);
+    retry_delete_count = itbl->retry_delete_count();
 
     for (int i = 0; i < 15; i++) {
         tid_ = 
@@ -166,6 +169,8 @@ TEST_F(DBTest, Basic) {
     }
 
     itbl->Unregister(7);
+    // There are pending registers. retry_delete_count is not incremented
+    EXPECT_EQ(itbl->retry_delete_count(), retry_delete_count);
 
     tid_ = 
         itbl->Register(boost::bind(&DBTest::DBTestListener, this, _1, _2));
@@ -173,8 +178,13 @@ TEST_F(DBTest, Basic) {
 
 
     for (int i = 14; i >=0; i--) {
+        EXPECT_EQ(itbl->retry_delete_count(), retry_delete_count);
         itbl->Unregister(i);
     }
+
+    // All clients are registered. retry_delete_count should be incremented
+    EXPECT_EQ(itbl->retry_delete_count(), retry_delete_count+1);
+    retry_delete_count = itbl->retry_delete_count();
 }
 
 // To Test: