Rework the frontend and backend to allow passing a ratio value in for
UseDelta rather than having a hardcoded #define-d 0.7 value always used.
This is useful for those with fast connections, who would likely benefit
from tuning this ratio to lower values; it is also useful for general
testing purposes.

The libalpm API changes for this, but we do support the old config file
format with a no-value 'UseDelta' option; in this case we simply use the
old default of 0.7.

We clamp the ratio values to a sane range between 0.0 and 2.0, allowing
ratios above 1.0 for testing purposes.

Signed-off-by: Dan McGee <dan@archlinux.org>
---
doc/pacman.conf.5.txt | 10 +++++++---
etc/pacman.conf.in | 2 +-
lib/libalpm/alpm.h | 4 ++--
lib/libalpm/delta.c | 3 ++-
lib/libalpm/delta.h | 3 ---
lib/libalpm/handle.c | 12 ++++++++----
lib/libalpm/handle.h | 2 +-
lib/libalpm/sync.c | 4 ++--
src/pacman/conf.c | 19 ++++++++++++++++---
src/pacman/conf.h | 2 +-
10 files changed, 40 insertions(+), 21 deletions(-)

diff --git a/doc/pacman.conf.5.txt b/doc/pacman.conf.5.txt
index 2c1a24b..3913292 100644
--- a/doc/pacman.conf.5.txt
+++ b/doc/pacman.conf.5.txt
@@ -168,9 +168,13 @@ Options
Log action messages through syslog(). This will insert log entries into
+{localstatedir}/log/messages+ or equivalent.

-*UseDelta*::
- Download delta files instead of complete packages if possible. Requires
- the xdelta3 program to be installed.
+*UseDelta* [= ratio]::
+ Download delta files instead of complete packages if possible. Requires
+ the `xdelta3` program to be installed. If a ratio is specified (e.g.,
+ `0.5`), then it is used as a cutoff for determining whether to use deltas.
+ Allowed values are between `0.0` and `2.0`; sensible values are between
+ `0.2` and `0.9`. Using a value above `1.0` is not recommended. The
+ default is `0.7` if left unspecified.

*TotalDownload*::
When downloading, display the amount downloaded, download rate, ETA,
diff --git a/etc/pacman.conf.in b/etc/pacman.conf.in
index 932140f..7f9db1b 100644
--- a/etc/pacman.conf.in
+++ b/etc/pacman.conf.in
@@ -20,6 +20,7 @@ SyncFirst = pacman
#XferCommand = /usr/bin/curl -C - -f %u > %o
#XferCommand = /usr/bin/wget --passive-ftp -c -O %o %u
#CleanMethod = KeepInstalled
+#UseDelta = 0.7
Architecture = auto

# Pacman won't upgrade packages listed in IgnorePkg and members of IgnoreGroup
@@ -31,7 +32,6 @@ Architecture = auto

# Misc options
#UseSyslog
-#UseDelta
#TotalDownload
CheckSpace
#VerbosePkgLists
diff --git a/lib/libalpm/alpm.h b/lib/libalpm/alpm.h
index 95c817e..9ffdebc 100644
--- a/lib/libalpm/alpm.h
+++ b/lib/libalpm/alpm.h
@@ -535,8 +535,8 @@ const char *alpm_option_get_arch(alpm_handle_t *handle);
/** Sets the targeted architecture. */
int alpm_option_set_arch(alpm_handle_t *handle, const char *arch);

-int alpm_option_get_usedelta(alpm_handle_t *handle);
-int alpm_option_set_usedelta(alpm_handle_t *handle, int usedelta);
+double alpm_option_get_deltaratio(alpm_handle_t *handle);
+int alpm_option_set_deltaratio(alpm_handle_t *handle, double ratio);

int alpm_option_get_checkspace(alpm_handle_t *handle);
int alpm_option_set_checkspace(alpm_handle_t *handle, int checkspace);
diff --git a/lib/libalpm/delta.c b/lib/libalpm/delta.c
index 726f03c..e3acc66 100644
--- a/lib/libalpm/delta.c
+++ b/lib/libalpm/delta.c
@@ -264,7 +264,8 @@ static alpm_list_t *find_unused(alpm_list_t *deltas, const char *to, off_t quota
alpm_list_t SYMEXPORT *alpm_pkg_unused_deltas(alpm_pkg_t *pkg)
{
ASSERT(pkg != NULL, return NULL);
- return find_unused(pkg->deltas, pkg->filename, pkg->size * MAX_DELTA_RATIO);
+ return find_unused(pkg->deltas, pkg->filename,
+ pkg->size * pkg->handle->deltaratio);
}

/** @} */
diff --git a/lib/libalpm/delta.h b/lib/libalpm/delta.h
index 1173ddf..37f208b 100644
--- a/lib/libalpm/delta.h
+++ b/lib/libalpm/delta.h
@@ -30,9 +30,6 @@ alpm_delta_t *_alpm_delta_dup(const alpm_delta_t *delta);
off_t _alpm_shortest_delta_path(alpm_handle_t *handle, alpm_list_t *deltas,
const char *to, alpm_list_t **path);

-/* max percent of package size to download deltas */
-#define MAX_DELTA_RATIO 0.7
-
#endif /* _ALPM_DELTA_H */

/* vim: set ts=2 sw=2 noet: */
diff --git a/lib/libalpm/handle.c b/lib/libalpm/handle.c
index 8e2e3c7..2187dca 100644
--- a/lib/libalpm/handle.c
+++ b/lib/libalpm/handle.c
@@ -43,6 +43,7 @@ alpm_handle_t *_alpm_handle_new(void)
alpm_handle_t *handle;

CALLOC(handle, 1, sizeof(alpm_handle_t), return NULL);
+ handle->deltaratio = 0.0;

return handle;
}
@@ -252,10 +253,10 @@ const char SYMEXPORT *alpm_option_get_arch(alpm_handle_t *handle)
return handle->arch;
}

-int SYMEXPORT alpm_option_get_usedelta(alpm_handle_t *handle)
+double SYMEXPORT alpm_option_get_deltaratio(alpm_handle_t *handle)
{
CHECK_HANDLE(handle, return -1);
- return handle->usedelta;
+ return handle->deltaratio;
}

int SYMEXPORT alpm_option_get_checkspace(alpm_handle_t *handle)
@@ -597,10 +598,13 @@ int SYMEXPORT alpm_option_set_arch(alpm_handle_t *handle, const char *arch)
return 0;
}

-int SYMEXPORT alpm_option_set_usedelta(alpm_handle_t *handle, int usedelta)
+int SYMEXPORT alpm_option_set_deltaratio(alpm_handle_t *handle, double ratio)
{
CHECK_HANDLE(handle, return -1);
- handle->usedelta = usedelta;
+ if(ratio < 0.0 || ratio > 2.0) {
+ RET_ERR(handle, ALPM_ERR_WRONG_ARGS, -1);
+ }
+ handle->deltaratio = ratio;
return 0;
}

diff --git a/lib/libalpm/handle.h b/lib/libalpm/handle.h
index a64c5c9..a090ae4 100644
--- a/lib/libalpm/handle.h
+++ b/lib/libalpm/handle.h
@@ -88,8 +88,8 @@ struct __alpm_handle_t {

/* options */
char *arch; /* Architecture of packages we should allow */
+ double deltaratio; /* Download deltas if possible; a ratio value */
int usesyslog; /* Use syslog instead of logfile? */ /* TODO move to frontend */
- int usedelta; /* Download deltas if possible */
int checkspace; /* Check disk space before installing */
alpm_siglevel_t siglevel; /* Default signature verification level */

diff --git a/lib/libalpm/sync.c b/lib/libalpm/sync.c
index 49a3f42..6967b49 100644
--- a/lib/libalpm/sync.c
+++ b/lib/libalpm/sync.c
@@ -318,13 +318,13 @@ static int compute_download_size(alpm_pkg_t *newpkg)

/* tell the caller that we have a partial */
ret = 1;
- } else if(handle->usedelta) {
+ } else if(handle->deltaratio > 0.0) {
off_t dltsize;

dltsize = _alpm_shortest_delta_path(handle, newpkg->deltas,
newpkg->filename, &newpkg->delta_path);

- if(newpkg->delta_path && (dltsize < newpkg->size * MAX_DELTA_RATIO)) {
+ if(newpkg->delta_path && (dltsize < newpkg->size * handle->deltaratio)) {
_alpm_log(handle, ALPM_LOG_DEBUG, "using delta size
");
size = dltsize;
} else {
diff --git a/src/pacman/conf.c b/src/pacman/conf.c
index 7ba2791..e1bff18 100644
--- a/src/pacman/conf.c
+++ b/src/pacman/conf.c
@@ -52,6 +52,7 @@ config_t *config_new(void)
newconfig->op = PM_OP_MAIN;
newconfig->logmask = ALPM_LOG_ERROR | ALPM_LOG_WARNING;
newconfig->configfile = strdup(CONFFILE);
+ newconfig->deltaratio = 0.0;
if(alpm_capabilities() & ALPM_CAPABILITY_SIGNATURES) {
newconfig->siglevel = ALPM_SIG_PACKAGE | ALPM_SIG_PACKAGE_OPTIONAL |
ALPM_SIG_DATABASE | ALPM_SIG_DATABASE_OPTIONAL;
@@ -397,8 +398,8 @@ static int _parse_options(const char *key, char *value,
config->verbosepkglists = 1;
pm_printf(ALPM_LOG_DEBUG, "config: verbosepkglists
");
} else if(strcmp(key, "UseDelta") == 0) {
- config->usedelta = 1;
- pm_printf(ALPM_LOG_DEBUG, "config: usedelta
");
+ config->deltaratio = 0.7;
+ pm_printf(ALPM_LOG_DEBUG, "config: usedelta (default 0.7)
");
} else if(strcmp(key, "TotalDownload") == 0) {
config->totaldownload = 1;
pm_printf(ALPM_LOG_DEBUG, "config: totaldownload
");
@@ -429,6 +430,18 @@ static int _parse_options(const char *key, char *value,
if(!config->arch) {
config_set_arch(value);
}
+ } else if(strcmp(key, "UseDelta") == 0) {
+ double ratio;
+ char *endptr;
+ ratio = strtod(value, &endptr);
+ if(*endptr != '' || ratio < 0.0 || ratio > 2.0) {
+ pm_printf(ALPM_LOG_ERROR,
+ _("config file %s, line %d: invalid value for '%s' : '%s'
"),
+ file, linenum, "UseDelta", value);
+ return 1;
+ }
+ config->deltaratio = ratio;
+ pm_printf(ALPM_LOG_DEBUG, "config: usedelta = %f
", ratio);
} else if(strcmp(key, "DBPath") == 0) {
/* don't overwrite a path specified on the command line */
if(!config->dbpath) {
@@ -605,7 +618,7 @@ static int setup_libalpm(void)
alpm_option_set_arch(handle, config->arch);
alpm_option_set_checkspace(handle, config->checkspace);
alpm_option_set_usesyslog(handle, config->usesyslog);
- alpm_option_set_usedelta(handle, config->usedelta);
+ alpm_option_set_deltaratio(handle, config->deltaratio);

alpm_option_set_ignorepkgs(handle, config->ignorepkg);
alpm_option_set_ignoregroups(handle, config->ignoregrp);
diff --git a/src/pacman/conf.h b/src/pacman/conf.h
index 325fbb6..481132f 100644
--- a/src/pacman/conf.h
+++ b/src/pacman/conf.h
@@ -34,7 +34,7 @@ typedef struct __config_t {
unsigned short print;
unsigned short checkspace;
unsigned short usesyslog;
- unsigned short usedelta;
+ double deltaratio;
char *arch;
char *print_format;
/* unfortunately, we have to keep track of paths both here and in the library
--
1.7.8.3

On 12/01/12 07:42, Dan McGee wrote:
> Rework the frontend and backend to allow passing a ratio value in for
> UseDelta rather than having a hardcoded #define-d 0.7 value always used.
> This is useful for those with fast connections, who would likely benefit
> from tuning this ratio to lower values; it is also useful for general
> testing purposes.
>
> The libalpm API changes for this, but we do support the old config file
> format with a no-value 'UseDelta' option; in this case we simply use the
> old default of 0.7.
>
> We clamp the ratio values to a sane range between 0.0 and 2.0, allowing
> ratios above 1.0 for testing purposes.
>
> Signed-off-by: Dan McGee <dan@archlinux.org>

Ack-by: Allan

Looks good from some basic testing here.

My only thought (which is possibly full of bikeshed, so feel free to
ignore...) was do we really want to stick with a ratio or move to an
absolute size difference? 0.9 of a 100MB package is much more useful
than 0.9 of a 1KB package.

Allan