From f02cb7bf4978ec0fa1eea4ed0b21460b7637d741 Mon Sep 17 00:00:00 2001
From: Chris Xiong <chirs241097@gmail.com>
Date: Sun, 18 Sep 2022 00:00:07 -0400
Subject: Add batching for get_signature().

---
 signature_db.cpp           | 28 ++++++++++++++++++++++++----
 signature_db.hpp           |  2 ++
 tests/testdrive_sqlite.cpp |  2 ++
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/signature_db.cpp b/signature_db.cpp
index 429581d..393b756 100644
--- a/signature_db.cpp
+++ b/signature_db.cpp
@@ -14,6 +14,7 @@ const int SIGDB_VERSION = 3;
 enum batch_status
 {
     none = 0,
+    getsig,
     putsub,
     findsub,
     setpar,
@@ -169,11 +170,20 @@ size_t signature_db::put_signature(const fs::path &path, const signature &sig,si
     return static_cast<size_t>(sqlite3_last_insert_rowid(p->db));
 }
 
+void signature_db::batch_get_signature_begin()
+{
+    if (!p->db) [[ unlikely ]] return;
+    sqlite3_prepare_v2(p->db, "select path, signature from images where id = ?;", -1, &p->bst[batch_status::getsig], 0);
+}
+
 std::pair<fs::path, signature> signature_db::get_signature(size_t id)
 {
     if (!p->db) [[ unlikely ]] return std::make_pair(fs::path(), signature());
-    sqlite3_stmt *st;
-    sqlite3_prepare_v2(p->db, "select path, signature from images where id = ?;", -1, &st, 0);
+    sqlite3_stmt *st = nullptr;
+    if (p->bst[batch_status::getsig])
+        st = p->bst[batch_status::getsig];
+    else
+        sqlite3_prepare_v2(p->db, "select path, signature from images where id = ?;", -1, &st, 0);
     sqlite3_bind_int(st, 1, id);
     int rr = sqlite3_step(st);
     if (rr == SQLITE_ROW)
@@ -184,15 +194,25 @@ std::pair<fs::path, signature> signature_db::get_signature(size_t id)
         fs::path path((char*)sqlite3_column_text(st, 0));
 #endif
         std::string sigs((char*)sqlite3_column_text(st, 1));
-        sqlite3_finalize(st);
+        if (p->bst[batch_status::getsig])
+            sqlite3_reset(st);
+        else
+            sqlite3_finalize(st);
         return std::make_pair(path, signature::from_string(std::move(sigs)));
     }
     else
     {
-        sqlite3_finalize(st);
+        if (p->bst[batch_status::getsig])
+            sqlite3_reset(st);
+        else
+            sqlite3_finalize(st);
         return std::make_pair(fs::path(), signature());
     }
 }
+void signature_db::batch_get_signature_end()
+{
+    p->batch_end(batch_status::getsig);
+}
 
 void signature_db::batch_put_subslice_begin()
 {
diff --git a/signature_db.hpp b/signature_db.hpp
index a56ae1f..b37cf0a 100644
--- a/signature_db.hpp
+++ b/signature_db.hpp
@@ -52,8 +52,10 @@ public:
     //if specificted, id must be unique
     //treat automatically assigned id as arbitrary opaque integers
     size_t put_signature(const fs::path &path, const signature &sig, size_t id = ~size_t(0));
+    void batch_get_signature_begin();
     //get image signature from database
     std::pair<fs::path, signature> get_signature(size_t id);
+    void batch_get_signature_end();
 
     //place batch_put_subslice_begin() and batch_put_subslice_end() around a group of
     //put_subslice() calls to improve performance
diff --git a/tests/testdrive_sqlite.cpp b/tests/testdrive_sqlite.cpp
index c9e9aad..66d1996 100644
--- a/tests/testdrive_sqlite.cpp
+++ b/tests/testdrive_sqlite.cpp
@@ -229,6 +229,7 @@ int main(int argc,char** argv)
     puts("grouping similar images...");
     sdb->group_similar();
 
+    sdb->batch_get_signature_begin();
     std::vector<dupe_t> dupes = sdb->dupe_pairs();
     for (auto &p : dupes)
     {
@@ -258,6 +259,7 @@ int main(int argc,char** argv)
 #endif
         }
     }
+    sdb->batch_get_signature_end();
 
     sdb->to_db_file("test.sigdb");
     delete sdb;
-- 
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