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curve-client-python-api_en.md

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中文版

Get a CBDClient object that interacts with the Curve cluster

import curvefs

# Get a CBDClient object that interacts with the back-end cluster. Different CBDClient objects can establish connections with different clusters
cbd1 = curvefs.CBDClient()
cbd2 = curvefs.CBDClient()

CBDClient initialization

import curvefs
cbd = curvefs.CBDClient()
  
# parameter: full path of curve-client configuration file
# return: return 0 if initialized successfully, -1 means failed
cbd.Init("/etc/curve/client.conf")

Create file

import curvefs
cbd = curvefs.CBDClient()
cbd.Init("/etc/curve/client.conf")  # subsequent examples omit the initialization process
 
# parameter: the three parameters are
#      file full path
#      user information
#      file size
# return: return 0 if create successfully, otherwise return an error code

# First initialize user information (the control plane interfaces of curvefs have user information verification, and user information needs to be passed in)
user = curvefs.UserInfo_t()
user.owner = "curve"
user.password = ""  # when the password is empty, it can be omitted

# Create a file with Create interface
cbd.Create("/curve", user, 10*1024*1024*1024)
  
# UserInfo definition
typedef struct UserInfo {
    char owner[256];       # username 
    char password[256];    # password
} UserInfo_t;

Get file information

# parameter: the three parameters are
#      filename
#      user information
#      fileInfo[exit parameter]
# return: return 0 if get successfully, otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Construct file information
finfo = curvefs.FileInfo_t()

# Get file information
cbd.StatFile("/curve", user, finfo)
print finfo.filetype
print finfo.length
print finfo.ctime
  
# FileInfo definition
typedef struct FileInfo {
    uint64_t      id;          
    uint64_t      parentid;
    int           filetype;   # volume type
    uint64_t      length;     # volume size
    uint64_t      ctime;      # volume create time
    char          filename[256];   # volume name
    char          owner[256];      # volume owner
    int           fileStatus;      # volume status
} FileInfo_t;
 
# File status
#define CURVE_FILE_CREATED            0
#define CURVE_FILE_DELETING           1
#define CURVE_FILE_CLONING            2
#define CURVE_FILE_CLONEMETAINSTALLED 3
#define CURVE_FILE_CLONED             4
#define CURVE_FILE_BEINGCLONED        5

Extend file

# parameter: the three parameters are
#      filename
#      user information
#      file size after extend
# return: return 0 if extend successfully, otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Extend
cbd.Extend("/curve", user, 20*1024*1024*1024)

# Get file information after extension
finfo = curvefs.FileInfo_t()
cbd.StatFile("/curve", user, finfo)
print finfo.length

Open/Close file

# Open file
# parameter: the two parameters are
#      filename
#      user information
# return: return fd if open successfully, otherwise return error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "user1"

# Open file，return fd
fd = cbd.Open("/tmp1", user)
  
# Close file
# parameter: fd returned when opening the file
# return: return 0 if closed successfully, otherwise return an error code
cbd.Close(fd)

Read and write file

# Write file
# parameter: the four parameters are
#      fd
#      data to write
#      offset
#      date length
# return: return the number of bytes written If write successful, otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "user1"

# Open file，return fd
fd = cbd.Open("/tmp1", user)

# Write files (Currently, 4k alignment is required for reading and writing)
cbd.Write(fd, "aaaaaaaa"*512, 0, 4096)
cbd.Write(fd, "bbbbbbbb"*512, 4096, 4096)
  
# Read file
# parameter: the four parameters are
#      fd
#      null string
#      offset
#      data length to read
# return: return read data if read successfully, otherwise return an error code

# The read content is returned by the return value, buf is not needed, you can pass in an empty string
cbd.Read(fd，"", 0, 4096)

# Close file
cbd.Close(fd)

Note: The current python api does not support asynchronous reading and writing

Delete file

# parameter: the two parameters are
#      filename
#      user information
# return: return 0 if delete successfully, otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Delete file
cbd.Unlink("/curve", user)

Recover file

# parameter: the three parameters are
#      filename
#      user information
#      file id (optional, default is 0)
# return: return 0 if recover successfully, otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Recover file
cbd.Recover("/curve", user, 0)

Rename file

# parameter: the three parameters are
#      user information
#      old filename
#      new filename
# return: return 0 if rename successfully,  otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Rename
cbd.Rename(user, "/curve", "/curve-new")

Create a directory

# parameter: the two parameters are
#      directory path
#      user information
# return: return 0 if create successfully,  otherwise return an error code

# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"
# Create directory
cbd.Mkdir("/curvedir", user)

Delete directory

# parameter: the two parameters are
#      directory path
#      user information
# return: return 0 if create successfully,  otherwise return an error code
  
# Construct user information
user = curvefs.UserInfo_t()
user.owner = "curve"

# Delete directory
cbd.Rmdir("/curvedir", user)

List the files in the directory

# parameter: the two parameters are
#      directory path
#      user information
# return: files in the directory (only filename)
files = cbd.Listdir("/test", user)
for f in files:
    print f

Get the cluster ID

# Determine whether this get is successful by the return value
# success: return cluster ID
# fail: return null string
clusterId = cbd.GetClusterId()
print clusterId
# c355675a-f4d2-4729-b80a-5a7bcc749d1c

Clean CBDClient object

cbd.UnInit()

Error code

Code Message description
0 OK success
-1 EXISTS file or directory exists
-2 FAILED fail
-3 DISABLEDIO disable io
-4 AUTHFAIL authentication failed
-5 DELETING deleting
-6 NOTEXIST file not exist
-7 UNDER_SNAPSHOT under snapshot
-8 NOT_UNDERSNAPSHOT not under snapshot
-9 DELETE_ERROR delete error
-10 NOT_ALLOCATE segment not allocated
-11 NOT_SUPPORT operation not supported
-12 NOT_EMPTY directory not empty
-13 NO_SHRINK_BIGGER_FILE no shrinkage
-14 SESSION_NOTEXISTS session not exist
-15 FILE_OCCUPIED file occupied
-16 PARAM_ERROR parameter error
-17 INTERNAL_ERROR internal error
-18 CRC_ERROR CRC error
-19 INVALID_REQUEST parameter invalid
-20 DISK_FAIL disk fail
-21 NO_SPACE no space
-22 NOT_ALIGNED io not aligned
-23 BAD_FD file is being closed, fd unavailable
-24 LENGTH_NOT_SUPPORT file length is not supported
-25 SESSION_NOT_EXIST session not exist, duplicate with -14
-26 STATUS_NOT_MATCH status error
-27 DELETE_BEING_CLONED delete the file being cloned
-28 CLIENT_NOT_SUPPORT_SNAPSHOT this version of client not support snapshot
-29 SNAPSHOT_FROZEN snapshot is disabled
-100 UNKNOWN unknown error