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authorLukas Larsson <lukas@erlang-solutions.com>2011-12-05 18:45:44 +0100
committerLukas Larsson <lukas@erlang-solutions.com>2011-12-05 19:39:40 +0100
commitec885e883c99825e7d737752b1b0aebbbafbd670 (patch)
tree113a30c70ca435b2d9f52d8dde7ca4e77860948f /erts/emulator/drivers
parent250a556b1e3eb8486ec294f94d3b918c9ac91542 (diff)
downloadotp-ec885e883c99825e7d737752b1b0aebbbafbd670.tar.gz
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otp-ec885e883c99825e7d737752b1b0aebbbafbd670.zip
Clarify some code comments
Thanks Tuncer Ayaz
Diffstat (limited to 'erts/emulator/drivers')
-rw-r--r--erts/emulator/drivers/common/erl_efile.h2
-rw-r--r--erts/emulator/drivers/common/inet_drv.c6
-rw-r--r--erts/emulator/drivers/unix/unix_efile.c16
3 files changed, 17 insertions, 7 deletions
diff --git a/erts/emulator/drivers/common/erl_efile.h b/erts/emulator/drivers/common/erl_efile.h
index ed8910a8b8..0ed4a60efb 100644
--- a/erts/emulator/drivers/common/erl_efile.h
+++ b/erts/emulator/drivers/common/erl_efile.h
@@ -126,7 +126,7 @@ typedef struct _Efile_info {
#ifdef HAVE_SENDFILE
/*
- * Described the structure of header/trailers for sendfile
+ * Describes the structure of headers/trailers for sendfile
*/
struct t_sendfile_hdtl {
SysIOVec *headers;
diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
index 56799555a9..abbd835605 100644
--- a/erts/emulator/drivers/common/inet_drv.c
+++ b/erts/emulator/drivers/common/inet_drv.c
@@ -872,9 +872,9 @@ typedef struct {
double send_avg; /* average packet size sent */
subs_list empty_out_q_subs; /* Empty out queue subscribers */
- int is_ignored; /* if a fd is ignored by from the inet_drv,
- this should be set to true when the fd is used
- outside of inet_drv. */
+ int is_ignored; /* if a fd is ignored by the inet_drv.
+ This flag should be set to true when
+ the fd is used outside of inet_drv. */
} inet_descriptor;
diff --git a/erts/emulator/drivers/unix/unix_efile.c b/erts/emulator/drivers/unix/unix_efile.c
index 2b68334ad7..92314fce36 100644
--- a/erts/emulator/drivers/unix/unix_efile.c
+++ b/erts/emulator/drivers/unix/unix_efile.c
@@ -1469,6 +1469,9 @@ efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset,
}
#ifdef HAVE_SENDFILE
+
+// For some reason the maximum size_t cannot be used as the max size
+// 3GB seems to work on all platforms
#define SENDFILE_CHUNK_SIZE ((1 << 30) -1)
/*
@@ -1477,7 +1480,13 @@ efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset,
* we have to emulate some things in linux and play with variables on
* bsd/darwin.
*
- * It could be possible to implement header/trailer in sendfile, though
+ * All of the calls will split a command which tries to send more than
+ * SENDFILE_CHUNK_SIZE of data at once.
+ *
+ * On platforms where *nbytes of 0 does not mean the entire file, this is
+ * simulated.
+ *
+ * It could be possible to implement header/trailer in sendfile. Though
* you would have to emulate it in linux and on BSD/Darwin some complex
* calculations have to be made when using a non blocking socket to figure
* out how much of the header/file/trailer was sent in each command.
@@ -1491,7 +1500,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd,
#if defined(__linux__)
ssize_t retval;
do {
- // check if *nbytes is 0 or greater than the largest size_t
+ // check if *nbytes is 0 or greater than chunk size
if (*nbytes == 0 || *nbytes > SENDFILE_CHUNK_SIZE)
retval = sendfile(out_fd, in_fd, offset, SENDFILE_CHUNK_SIZE);
else
@@ -1512,6 +1521,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd,
do {
fdrec.sfv_off = *offset;
len = 0;
+ // check if *nbytes is 0 or greater than chunk size
if (*nbytes == 0 || *nbytes > SENDFILE_CHUNK_SIZE)
fdrec.sfv_len = SENDFILE_CHUNK_SIZE;
else
@@ -1529,7 +1539,7 @@ efile_sendfile(Efile_error* errInfo, int in_fd, int out_fd,
int retval;
off_t len;
do {
- // check if *nbytes is 0 or greater than the largest off_t
+ // check if *nbytes is 0 or greater than chunk size
if(*nbytes > SENDFILE_CHUNK_SIZE)
len = SENDFILE_CHUNK_SIZE;
else