From bf665f59411840c60b6e3c9ac33f28a818233c0a Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 5 Sep 2019 18:15:52 +0200
Subject: [SERVER] Introduce autoFreeDiskSpaceDelay

This setting allows you to control the formerly hard-coded timeout of 10
hours before a proxy would start deleting old images in order to free up
space for new images. Setting it to -1 entirely disables automatic
deletion, in case you have an external process for freeing up disk
space.
---
 conf/server.conf     | 11 +++++++++++
 src/server/globals.c | 12 ++++++++++++
 src/server/globals.h |  7 +++++++
 src/server/image.c   | 14 ++++++++------
 4 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/conf/server.conf b/conf/server.conf
index a101f34..a15092f 100644
--- a/conf/server.conf
+++ b/conf/server.conf
@@ -31,6 +31,17 @@ vmdkLegacyMode=false
 ; Don't set the server flag when connecting to alt-servers
 ; Intended for if the proxy is used for on-client caching
 pretendClient=false
+; When running in proxy mode and running out of space, automatically delete oldest image(s) to make
+; the newly replicated image fit. In sparse mode, this will make sure at least 2GB of free space are
+; available when replicating a new image. During normal operation, it will free at least 256MB whenever
+; an attempt to write more data to cache fails. In non-sparse mode, whenever a new image is replicated,
+; as much space as is required to store the entire image will be made available.
+; However, after startup the proxy will refuse to delete any images for the time span given below, to be
+; able to gather up to date usage information for the images available. If unitless, the value is
+; interpreted in seconds. Valid suffixes are m, h, d.
+; Setting this to -1 disables deletion of images. If the cache partition is full, no more images will
+; be replicated unless you manually free up more disk space.
+autoFreeDiskSpaceDelay=10h
 
 [limits]
 maxClients=2000
diff --git a/src/server/globals.c b/src/server/globals.c
index 46c1030..f8c3f66 100644
--- a/src/server/globals.c
+++ b/src/server/globals.c
@@ -28,6 +28,7 @@ atomic_bool _closeUnusedFd = false;
 atomic_bool _vmdkLegacyMode = false;
 // Not really needed anymore since we have '+' and '-' in alt-servers
 atomic_bool _proxyPrivateOnly = false;
+atomic_int _autoFreeDiskSpaceDelay = 3600 * 10;
 // [limits]
 atomic_int _maxClients = SERVER_MAX_CLIENTS;
 atomic_int _maxImages = SERVER_MAX_IMAGES;
@@ -83,6 +84,7 @@ static int ini_handler(void *custom UNUSED, const char* section, const char* key
 	SAVE_TO_VAR_UINT( limits, maxPayload );
 	SAVE_TO_VAR_UINT64( limits, maxReplicationSize );
 	SAVE_TO_VAR_BOOL( dnbd3, pretendClient );
+	SAVE_TO_VAR_INT( dnbd3, autoFreeDiskSpaceDelay );
 	if ( strcmp( section, "dnbd3" ) == 0 && strcmp( key, "backgroundReplication" ) == 0 ) {
 		if ( strcmp( value, "hashblock" ) == 0 ) {
 			_backgroundReplication = BGR_HASHBLOCK;
@@ -229,6 +231,15 @@ static bool parse64(const char *in, atomic_int_fast64_t *out, const char *optnam
 	while ( *end == ' ' ) end++;
 	if ( *end == '\0' ) {
 		exp = 0;
+	} else if ( *end == 'm' ) {
+		exp = 1;
+		base = 60;
+	} else if ( *end == 'h' ) {
+		exp = 1;
+		base = 3600;
+	} else if ( *end == 'd' ) {
+		exp = 1;
+		base = 24 * 3600;
 	} else {
 		char *pos = strchr( units, *end > 'Z' ? (*end - 32) : *end );
 		if ( pos == NULL ) {
@@ -318,6 +329,7 @@ size_t globals_dumpConfig(char *buffer, size_t size)
 	PBOOL(vmdkLegacyMode);
 	PBOOL(proxyPrivateOnly);
 	PBOOL(pretendClient);
+	PINT(autoFreeDiskSpaceDelay);
 	P_ARG("[limits]\n");
 	PINT(maxClients);
 	PINT(maxImages);
diff --git a/src/server/globals.h b/src/server/globals.h
index ebdc1c7..58b2c9d 100644
--- a/src/server/globals.h
+++ b/src/server/globals.h
@@ -290,6 +290,13 @@ extern atomic_uint_fast64_t _maxReplicationSize;
  */
 extern atomic_bool _pretendClient;
 
+/**
+ * Minimum uptime in seconds before proxy starts deleting old
+ * images if running out of space. -1 disables automatic deletion.
+ * Only relevant in proxy mode.
+ */
+extern atomic_int _autoFreeDiskSpaceDelay;
+
 /**
  * Load the server configuration.
  */
diff --git a/src/server/image.c b/src/server/image.c
index 86e6b87..9fcb866 100644
--- a/src/server/image.c
+++ b/src/server/image.c
@@ -1696,14 +1696,16 @@ static bool image_ensureDiskSpace(uint64_t size, bool force)
 	for ( int maxtries = 0; maxtries < 20; ++maxtries ) {
 		uint64_t available;
 		if ( !file_freeDiskSpace( _basePath, NULL, &available ) ) {
-			const int e = errno;
-			logadd( LOG_WARNING, "Could not get free disk space (errno %d), will assume there is enough space left... ;-)\n", e );
+			logadd( LOG_WARNING, "Could not get free disk space (errno %d), will assume there is enough space left... ;-)\n", errno );
 			return true;
 		}
-		if ( available > size ) return true;
-		if ( !force && dnbd3_serverUptime() < 10 * 3600 ) {
-			logadd( LOG_INFO, "Only %dMiB free, %dMiB requested, but server uptime < 10 hours...", (int)(available / (1024ll * 1024ll)),
-					(int)(size / (1024 * 1024)) );
+		if ( available > size )
+			return true; // Yay
+		if ( !_isProxy || _autoFreeDiskSpaceDelay == -1 )
+			return false; // If not in proxy mode at all, or explicitly disabled, never delete anything
+		if ( !force && dnbd3_serverUptime() < (uint32_t)_autoFreeDiskSpaceDelay ) {
+			logadd( LOG_INFO, "Only %dMiB free, %dMiB requested, but server uptime < %d minutes...", (int)(available / (1024ll * 1024ll)),
+					(int)(size / (1024 * 1024)), _autoFreeDiskSpaceDelay / 60 );
 			return false;
 		}
 		logadd( LOG_INFO, "Only %dMiB free, %dMiB requested, freeing an image...", (int)(available / (1024ll * 1024ll)),
-- 
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