From 23668b14830611cd3ac037f323b0e60a67a8dc3d Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <steinar+git@gunderson.no>
Date: Sat, 28 Nov 2020 18:17:23 +0100
Subject: [PATCH] =?utf8?q?Honor=20the=20=E2=80=9Crequire=20visibility?=
 =?utf8?q?=E2=80=9D=20flag=20(in=20the=20negative).?=
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---
 access_rx_cache.cpp | 5 +++++
 access_rx_cache.h   | 5 +++--
 db.h                | 3 +++
 plocate.cpp         | 8 ++++++--
 4 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/access_rx_cache.cpp b/access_rx_cache.cpp
index c6f5634..a16a1fc 100644
--- a/access_rx_cache.cpp
+++ b/access_rx_cache.cpp
@@ -11,6 +11,11 @@ using namespace std;
 
 void AccessRXCache::check_access(const char *filename, bool allow_async, function<void(bool)> cb)
 {
+	if (!require_visibility) {
+		cb(true);
+		return;
+	}
+
 	lock_guard<mutex> lock(mu);
 	if (engine == nullptr || !engine->get_supports_stat()) {
 		allow_async = false;
diff --git a/access_rx_cache.h b/access_rx_cache.h
index 8757b94..80383ea 100644
--- a/access_rx_cache.h
+++ b/access_rx_cache.h
@@ -12,8 +12,8 @@ class IOUringEngine;
 
 class AccessRXCache {
 public:
-	AccessRXCache(IOUringEngine *engine)
-		: engine(engine) {}
+	AccessRXCache(IOUringEngine *engine, bool require_visibility)
+		: engine(engine), require_visibility(require_visibility) {}
 	void check_access(const char *filename, bool allow_async, std::function<void(bool)> cb);
 
 private:
@@ -25,6 +25,7 @@ private:
 	std::map<std::string, std::vector<PendingStat>> pending_stats;
 	IOUringEngine *engine;
 	std::mutex mu;
+	bool require_visibility;
 };
 
 #endif  // !defined(_ACCESS_RX_CACHE_H)
diff --git a/db.h b/db.h
index e23d478..722e567 100644
--- a/db.h
+++ b/db.h
@@ -24,6 +24,9 @@ struct Header {
 	uint64_t next_zstd_dictionary_offset_bytes;
 	uint64_t conf_block_length_bytes;
 	uint64_t conf_block_offset_bytes;
+
+	// Only if max_version >= 2.
+	bool require_visibility;
 };
 
 struct Trigram {
diff --git a/plocate.cpp b/plocate.cpp
index 6fe46a4..4f88b4b 100644
--- a/plocate.cpp
+++ b/plocate.cpp
@@ -105,6 +105,10 @@ Corpus::Corpus(int fd, IOUringEngine *engine)
 		hdr.zstd_dictionary_offset_bytes = 0;
 		hdr.zstd_dictionary_length_bytes = 0;
 	}
+	if (hdr.max_version < 2) {
+		// This too. (We ignore the other max_version 2 fields.)
+		hdr.require_visibility = true;
+	}
 }
 
 Corpus::~Corpus()
@@ -230,7 +234,7 @@ void scan_file_block(const vector<Needle> &needles, string_view compressed,
 size_t scan_docids(const vector<Needle> &needles, const vector<uint32_t> &docids, const Corpus &corpus, IOUringEngine *engine)
 {
 	Serializer docids_in_order;
-	AccessRXCache access_rx_cache(engine);
+	AccessRXCache access_rx_cache(engine, corpus.get_hdr().require_visibility);
 	atomic<uint64_t> matched{ 0 };
 	for (size_t i = 0; i < docids.size(); ++i) {
 		uint32_t docid = docids[i];
@@ -306,7 +310,7 @@ uint64_t scan_all_docids(const vector<Needle> &needles, int fd, const Corpus &co
 		}
 	}
 
-	AccessRXCache access_rx_cache(nullptr);
+	AccessRXCache access_rx_cache(nullptr, corpus.get_hdr().require_visibility);
 	Serializer serializer;
 	uint32_t num_blocks = corpus.get_num_filename_blocks();
 	unique_ptr<uint64_t[]> offsets(new uint64_t[num_blocks + 1]);
-- 
2.39.2